KR20160094129A - Method and apparatus for sensing current of orgainc emitting diode display device - Google Patents

Abstract

The present invention relates to a current sensing method of an OLED display device capable of removing noise from sensing current and an apparatus thereof. The current sensing apparatus according to the present invention comprises a data driver, wherein the data driver includes: a data providing unit for providing data signals for each sub-pixel of the display device; a sensing unit for outputting pixel information by sensing pixel current of the each operated sub-pixel; and a current source for providing current for the sensing unit. Before sensing the pixel current, the sensing unit uses the current source to sense output by channel according to properties of sensing channels of the sensing unit and to sense noise via an adjacent sensing channel, and deduct noise from each sensed channel, thereby outputting as information of each channel.

Description

Technical Field [0001] The present invention relates to an organic light emitting diode (OLED) display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting diode (OLED) display device, and more particularly, to a current sensing method and apparatus of an OLED display device capable of removing noise from a sensing current.

2. Description of the Related Art Recently, flat panel display devices that display images using digital data include liquid crystal displays (LCDs) using liquid crystals, OLED display devices using OLEDs, electrophoretic displays (EPDs) using electrophoretic particles ).

Of these, OLED display devices are self-luminous devices that emit organic light-emitting layers by recombination of electrons and holes, and are expected to be a next-generation display device because of their high luminance, low driving voltage, and ultra thin films.

Each of the plurality of pixels or subpixels 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 switching thin film transistor (TFT) for supplying a data voltage to the storage capacitor to charge a voltage corresponding to the data voltage, and a control circuit for controlling the current according to the voltage charged in the storage capacitor to supply the OLED element A driving TFT, and the like, and the OLED element generates light proportional to the current.

OLED display devices may have characteristics such as threshold voltage and mobility of the driving TFT, threshold voltage of the OLED element, and the like deteriorated by the driving time and the deterioration deviation of the driving TFT and the OLED element Thereby causing a luminance non-uniformity phenomenon. To solve this problem, an external compensation method for detecting and compensating the characteristics of the driving TFT and the OLED element is used.

For example, the external compensation method senses a current or a voltage indicating the characteristics of each driving TFT and the OLED element, calculates a compensation value for compensating the characteristics of the driving TFT and the OLED element based on the sensing information, , And compensates data to be supplied to each subpixel using the stored compensation value.

The method of sensing the current among the external compensation methods is to calibrate the offset (offset) and gain (gain) according to the channel characteristics of the sensing block using an external ideal current source before sensing the pixel current ), The sensing data is corrected by reflecting the stored offset and gain when sensing the pixel current.

However, when noise is included in a current source or the like, there is a problem that a sensing value sensed in the calibration process of the sensing block includes a noise component, so that an accurate sensing value can not be obtained. Accordingly, there is a problem that the offset and gain extracted from the sensing value including the noise component, and the error data due to the noise are included in the sensing data reflecting the offset and gain, so that the uneven luminance can not be compensated accurately.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a current sensing method and apparatus for an OLED display capable of removing noise from a sensing current.

According to an aspect of the present invention, there is provided a current sensing apparatus for an OLED display including a display panel and a data driver. The display panel includes a plurality of sub-pixels. The data driver includes a data supply unit for supplying a data signal to each sub pixel of the display panel, a sensing unit for sensing the pixel current of each driven sub pixel to output pixel information, and a current source for supplying a current to the sensing unit .

Before sensing the pixel current, the sensing unit senses the output according to the characteristics of the sensing channels of the sensing unit using the current source, senses the noise through the adjacent sensing channel, subtracts the noise from each sensed channel output, And outputs it as channel information.

The current sensing device of the present invention further includes a timing controller connected to the data driver. The timing controller includes an offset / gain extracting unit for extracting an offset and gain for comparing the channel information supplied from the sensing unit with the input current information of the current source to compensate for the characteristic difference of the sensing channels, and storing the offset and gain in the LUT1, A compensation value extracting unit for correcting the supplied pixel information using the offset and gain from the LUT 1, extracting a compensation value according to the characteristics of each subpixel from the corrected pixel information, and storing the compensation value in the LUT 2, And compensates data to be supplied to each sub-pixel and outputs the compensated data to the data driver.

The sensing unit includes a current-voltage conversion unit that converts a current source or an input current supplied from the display panel into a sensing voltage through integration on a channel basis, and a noise sensing unit that detects a noise sensed from an adjacent channel from a sensing voltage of each channel of the current- And a pixel sensing value sensing the pixel current from the display panel through the channel sensing value or the current-voltage conversion unit supplied from the noise suppression unit to digital data, Or an ADC that outputs pixel information.

The current-voltage conversion unit is connected to the plurality of sensing lines of the display panel separately and has a plurality of sensing channels connected in common to the current source. Each of the plurality of sensing channels includes a first input switch connected to a current source, a second input switch connected to any one of the plurality of sensing lines, and a second input switch connected to the first and second input switches, And a sampling and holder for sampling and holding the sensing voltage from the current integrator and outputting the sensing voltage.

The sensing unit may include a first multiplexer for selecting one of the plurality of sensing channels to select a sensing voltage from the selected sensing channel and outputting the sensed voltage to a noise removing unit, And a second multiplexer for outputting the noise sensed from the adjacent channel to the noise eliminator.

The noise removing unit subtracts the noise from the second multiplexer from the sensing voltage from the first multiplexer and outputs it as a channel sensing value.

The current-voltage converter further includes a dummy sensing channel for noise sensing adjacent to the first or the last sensing channel, which is disposed adjacent to the first or the last sensing channel among the plurality of sensing channels.

The plurality of sensing channels sequentially integrate the input current from the current source to output a sensing voltage, and the sensing channel adjacent to the sensing channel outputs an output generated without an input current from the current source as noise each time the sensing voltage is output .

A method of sensing a current of an OLED display according to an exemplary embodiment of the present invention includes sensing an output according to characteristics of sensing channels of a sensing unit using a current source, And outputting the channel information by subtracting the noise from the adjacent sensing channel from the output of the sensing channel.

The current sensing method of the present invention includes the steps of: comparing channel information with input current information of a current source to extract an offset and a gain for compensating for a characteristic difference of sensing channels, and storing the offset and gain in the LUT1; Sensing the pixel current supplied from the driven subpixel in the sensing unit and outputting it as pixel information; correcting the pixel information using offset and gain from LUT1; Extracting the compensation value, and storing the compensation value in the LUT2.

Sensing the output of the sensing channel includes sequentially inputting the input current supplied from the current source and integrating the input current for each sensing channel to output the sensing voltage.

The step of sensing the noise includes outputting noise generated without an input current from a sensing channel adjacent to the sensing channel every time a sensing voltage is output from the sensing channel.

The sensing voltage of the first or the last sensing channel among the plurality of sensing channels is subtracted from the noise sensed from the dummy sensing channel adjacent to the first or last sensing channel.

A method and apparatus for current sensing of an OLED display device according to the present invention includes sensing an output current for each channel in a calibration process of a sensing unit using a current source and sensing noise through an adjacent sensing channel to remove noise from the channel sensing value, The accurate offset and gain can be extracted and stored from the channel sensing value.

Therefore, the current sensing method and apparatus of the OLED display according to the present invention compensates the sensing data (pixel information) by reflecting the correct offset and gain when sensing the pixel current, and from the sensing data (pixel information) By extracting and storing the compensation value according to the characteristic, the uneven brightness can be compensated by using the stored compensation value.

1 is a block diagram schematically showing a current sensing device of an OLED display according to an embodiment of the present invention.
FIG. 2 is an equivalent circuit diagram showing the structure of one subpixel shown in FIG. 1, for example.
FIG. 3 is a view for explaining the sensing mode of the current sensing device shown in FIG. 1 step by step.
4 is a block diagram showing an internal configuration of the data driver shown in FIG.
5 is a circuit diagram specifically showing the sensing unit shown in FIG.
FIG. 6 is an equivalent circuit diagram showing embodiments of the noise removing unit shown in FIG. 5. FIG.
7 is a graph showing sensing data of each channel by the current sensing device of the OLED display according to the present invention.
FIG. 8 is a graph illustrating a noise removing effect of the current sensing device of the OLED display device according to the present invention in comparison with the conventional art.

1 is a block diagram schematically showing a current sensing device of an OLED display according to an embodiment of the present invention.

The current sensing device of the OLED display shown in FIG. 1 includes a display panel 100, a data driver 200, a timing controller 300, a memory 400, and the like.

The display panel 100 includes a pixel array in the form of a matrix and each pixel of the pixel array has R (Red), G (Green), B (Blue) subpixels SP, White) sub-pixels SP. Each sub-pixel SP includes a pixel circuit for independently supplying an OLED element and a current proportional to the data signal supplied from the data driver 200 to the OLED element.

The data driver 200 includes a data supply unit 210 for supplying a data signal to the display panel 100, a sensing unit 220 for sensing a pixel current from each subpixel SP of the display panel 100, A current source 230 for supplying a current to the unit 220, and the like. The data driver 200 further supplies a reference voltage Vref (FIG. 2) or a high potential power supply (EVDD) (FIG. 2) necessary for driving each subpixel SP.

The data supply unit 210 converts the digital data input from the timing controller 300 into analog data signals in the display mode and the sensing mode, respectively, and outputs the analog data signals to the data lines of the display panel 100.

The sensing unit 220 senses a pixel current output from the sub pixels SP driven using the sensing data signal supplied from the data supply unit 210 and supplies the sensing result to the timing controller 300 as pixel information do. The pixel information of each subpixel SP has characteristic information of a driving TFT such as a threshold voltage and a mobility of the driving TFT DT and deterioration information of the OLED element such as a threshold voltage of the OLED element, The threshold voltage, the mobility, and the threshold voltage of the OLED device.

The sensing unit 220 senses an output current varying according to channel characteristics (resistance, capacitance, etc.) of the sensing unit 220 using the ideal current source 230 in the calibration step before sensing the pixel current, And supplies the result to the timing controller 300 as channel information. At this time, the sensing unit 220 senses the output current for each channel using the current source 230, senses the noise through the adjacent channel, removes the noise from the output sensing value, and outputs the noise as a channel sensing value. Accordingly, the sensing unit 220 may convert the channel sensing value, which is input through the current source 230 or the like, into digital data, and output the channel sensing value to the timing controller 300 .

The timing controller 300 includes an offset / gain extracting unit (hereinafter, referred to as an offset / gain extracting unit) 410 for extracting an offset and a gain from the channel information supplied from the data driver 200 and storing the extracted offset and gain in a first look- And compensates the pixel information supplied from the data driver 200 by using the offset / gain from the LUT1 410 and extracts compensation values of the respective subpixels, (LUT2) 420, a data processing unit 330 for compensating data to be supplied to each subpixel using the compensation values from the LUT2 420 and outputting the compensation data, And a control signal generator 340 for generating and outputting control signals for controlling driving of the driver 200 and the like.

The offset / gain extracting unit 310 extracts the channel information supplied from the sensing unit 220 of the data driver 200 in the calibration mode of the sensing mode from the input current of the current source 230, And an offset and a gain that can be compensated for the channel-specific characteristic deviation of the sensing unit 220 are extracted and the extracted offset and gain are stored in the LUT1 410 of the memory 400. [

The compensation value extracting unit 320 compensates the pixel information supplied from the sensing unit 220 of the data driver 200 in the sensing mode by using the offset and gain from the LUT1 410, The compensation values for compensating the characteristics of the pixel are extracted and stored in the LUT2 420 of the memory 400. [ The compensation values of each subpixel stored in the LUT2 420 include a first compensation value for compensating for the threshold voltage of the driving TFT, a second compensation value for compensating for the mobility deviation of the driving TFT, Lt; RTI ID = 0.0 > a < / RTI >

The data processing unit 330 compensates the input image data or the sensing data using the compensation values stored in the LUT2 420 and outputs the compensated data to the data driver 200 in each of the display mode and the sensing mode.

The control signal generator 340 generates a data control signal and a gate control signal for controlling the driving timings of the data driver 200 and the gate driver (not shown) using a plurality of timing signals input from the outside, And outputs it to the driver 200 and the gate driver. For example, the control signal generator 340 controls the driving timing of the data driver 200 using a plurality of timing signals, such as a clock signal, a data enable signal, a horizontal synchronizing signal, a vertical synchronizing signal, A plurality of data control signals including a source start pulse, a source sampling clock, a source output enable signal, and the like, and a plurality of gate control signals including gate start pulses, gate shift clocks, And outputs it.

FIG. 2 is an equivalent circuit diagram showing the structure of one subpixel shown in FIG. 1, for example.

2, each sub-pixel SP includes an OLED element and a pixel circuit for driving the OLED element, and the pixel circuit includes first and second switching TFTs ST1 and ST2, a driving TFT DT, A storage capacitor Cst, and the like, but the pixel circuit is not limited to the configuration of FIG.

The first and second switching TFTs ST1 and ST2 and the driving TFT DT may be formed of an amorphous silicon (a-Si) TFT, a poly-Si TFT, an oxide TFT, Etc. may be used.

The OLED element has an anode connected to the driving TFT (DT), a cathode connected to the low potential voltage (EVSS), and a light emitting layer between the anode and the cathode. The anode is independent for each subpixel, but the cathode is shared by all the subpixels. The light emitting layer may include a hole injecting layer, a hole transporting layer, an organic light emitting layer, an electron transporting layer, and an electron injecting layer sequentially stacked between the anode and the cathode, and may include a functional layer for improving the light emitting efficiency and / . In the OLED element, when a positive bias is applied between the anode and the cathode, electrons from the cathode are supplied to the organic light emitting layer via the electron injection layer and the electron transport layer, and holes from the anode are injected into the organic light emitting layer via the hole injection layer and the hole transport layer . Accordingly, the organic light emitting layer emits fluorescence or phosphorescent material by recombination of the supplied electrons and holes, thereby generating light proportional to the amount of current supplied from the driving TFT DT.

The first switching TFT ST1 supplies the data voltage Vdata from the data line DL to the gate node N1 of the driving TFT DT in accordance with the scanning signal SC of one gate line GL1.

The second switching TFT ST2 supplies the reference voltage Vref from the reference line RL to the source node N2 of the driving TFT DT in accordance with the sensing control signal SE of the other gate line GL2 . The second switching TFT ST2 can be further used as a path for outputting the current from the driving TFT DT or the OLED element to the reference line RL in accordance with the sensing control signal SE in the sensing mode.

The storage capacitor Cst receives the data voltage Vdata supplied to the gate node N1 through the first switching TFT ST1 and the reference voltage Vdata supplied to the source node N2 through the second switching TFT ST2 (Vdata-Vref) of the driving TFT DT to the driving voltage Vgs of the driving TFT DT.

The driving TFT DT controls the current supplied from the supply line PL of the high potential voltage EVDD in accordance with the driving voltage Vgs charged in the storage capacitor Cst so that a current proportional to the driving voltage Vgs Ids) to the OLED element to emit the OLED element.

FIG. 3 is a view for explaining the sensing mode of the current sensing device shown in FIG. 1 step by step.

Referring to FIG. 3 (a), the current sensing device performs a calibration step of the sensing unit 220 using the current source 230 in the sensing mode.

In the calibration step, the sensing unit 220 integrates the input current from the current source 230 in a channel sequential manner to sense an output current including characteristics for each channel, and outputs a noise And the noise is removed from the channel sensing value. The sensing unit 220 converts the noise-removed channel sensing value into digital data and supplies it to the offset / gain extracting unit 310 of the timing controller 300 as channel information. At this time, the sensing unit 220 removes noise from the channel sensing value, sequentially converts the channel sensing value, and outputs the channel information. The offset / gain extracting unit 310 compares the channel information supplied from the sensing unit 220 with the input current information of the current source 230, extracts offset / gain for each channel, and stores the offset / gain in the LUT1 410. Such a calibration step may be performed only in the initial sensing mode before shipment or may be performed as an initial stage of the real time sensing mode whenever necessary after shipment of the product.

Referring to FIG. 3 (b), the current sensing device performs a step of sensing the pixel current of the display panel 100 in the sensing mode.

The sensing data supplied from the data processing unit 330 of the timing controller 300 is converted into an analog data signal through the data supply unit 220 of the data driver 200 and supplied to the corresponding subpixel of the display panel 100, The subpixel is driven in accordance with the data for sensing.

The sensing unit 220 senses a pixel current output from the driven sub-pixel through a sensing line such as a reference line or a data line, converts the sensed pixel current into digital data, and outputs the sensed pixel current to the compensation value extracting unit 320 of the timing controller 300 Information. The compensation value extracting unit 320 compensates the pixel information supplied from the sensing unit 220 by using the offset / gain from the LUT1 410, extracts compensation values according to the characteristics of the respective subpixels, . The compensation values for each subpixel stored in the LUT2 420 are stored through the initial sensing mode before shipment, and at least one of the power-on boot time, the power-off end time, the blanking period of each frame, Lt; RTI ID = 0.0 &

4 is a block diagram showing an internal configuration of the data driver shown in FIG.

The data driver 200 shown in FIG. 4 includes a data supply unit 210, a sensing unit 220, a current source 230, and the like.

The data supply unit 210 includes a shift register 211 for generating a sampling signal using a source start pulse and a source sampling clock from the timing controller 300 and a timing controller The first latch unit 212 and the second latch unit 213 sequentially latch the digital data from the first latch unit 300 and then latch and output the digital data sequentially. (Hereinafter referred to as DAC) 214 for converting the digital data from the DAC unit 213 into an analog data signal Vdata and outputting the analog data signal Vdata, And an output buffer 216 for outputting data to the data lines DL.

The sensing unit 220 includes a current-voltage conversion unit 222 that converts an input current per channel from the display panel 100 or the current source 230 into a voltage through current integration and outputs the voltage as a current sensing value, A noise removing unit 224 for removing noise sensed through the adjacent channel from the actual sensing value for each channel of the current-to-voltage converting unit 222 using the noise removal unit 224 to output a channel sensing value, Which outputs the channel information or pixel information to the timing controller 300 by bypassing the noise removal unit 224 from the current-voltage conversion unit 222 or converting the supplied pixel sensing value into digital data, To-digital converter (hereinafter referred to as ADC) 226.

5 is a circuit diagram specifically showing the sensing unit shown in FIG.

5 includes a current-to-voltage converter 222, a first multiplexer (MUX1) 223, a second multiplexer (MUX2) 225, a noise removing unit 224, an ADC (226).

The current-to-voltage conversion unit 222 includes n (n is a natural number) sensing channels CH1 to CHn connected to the current source 230 and the sensing lines SL1 to SLn of the display panel 100. [ The plurality of sensing channels CH1 to CHn includes first input switches SW11 to SW1n connected to the current source 230 and second input switches SW1 to SWn connected to the sensing lines SL1 to SLn of the display panel 100, The current integrators A1 to An connected one-to-one with the first input switches SW11 to SW1n and the second input switches SW21 to SW2n, the current integrators A1 to An, One-to-one connected sampling / holders SH1 to SHn, and each of the current integrators A1 to An further includes a feedback capacitor Cfb connected between the input and output terminals.

The current-voltage conversion unit 222 may further include one dummy sensing channel CHn + 1 connected to the current source 230. [ The dummy sensing channel CHn + 1 includes an input switch SWn + 1, an electric current integrator An + 1, a sampling / holder SHn + 1 connected to the current source 230, And a feedback capacitor Cfb connected between the input and output terminals. In FIG. 5, the dummy sensing channel CHn + 1 is disposed adjacent to the last sensing channel CHn but is not limited thereto and may be disposed adjacent to the first sensing channel CH1. For convenience of description, only the case where the dummy sensing channel CHn + 1 is disposed adjacent to the last sensing channel CHn will be described below as an example.

The first input switches SW11 to SW1n and SWn + 1 are sequentially turned on in the calibration step of the sensing mode to sequentially supply the input current from the current source 230 to the current integrators A1 to An.

The second input switches SW21 to SW2n are turned on in the sensing mode to output the input current (i.e., the pixel current) from the sensing lines SL1 to SLn of the display panel 100 to the current integrators A1 to An ), Respectively. The sensing lines SL1 to SLn may be reference lines or data lines connected to the subpixels of the display panel 100. [

Each of the current integrators A1 to An + 1 is connected to one of the first input switches SW1 #, # = 1, 2, ..., n + 1 or the second input switches SW2 # ..., n), and the other input terminal is connected to the reference voltage Vref to integrate the input current and output it as the sensing voltage to the output terminal. The sampling / holders SH1 to SHn, SHdm ) Samples and holds the sensing voltage output from the corresponding current integrator (A #, # = 1, 2, ..., n + 1) and outputs it.

In the calibration step of the sensing unit 220, a plurality of sensing channels CH1 to CHn successively integrate the input current from the current source 230 to output a sensing voltage, and each time a sensing voltage is output for each channel, Any one adjacent channel senses noise and outputs it.

The MUX1 223 selects any one of the sensing channels CH1 through CHn + 1 to output the sensing voltage of the selected sensing channel, and the MUX2 225 outputs the sensing voltage of the selected sensing channel adjacent to the sensing channel selected by the MUX1 223 The output of the sensing channel is selected to output the noise component.

The noise eliminator 224 subtracts the noise from the MUX2 225 from the sensing voltage output from the MUX1 223 to output the noise-canceled sensing voltage through the ADC 226. [

For example, when sensing the first sensing channel CH1 in the calibration step of the sensing unit 220, only the first input switch SW11 of the first sensing channel CH1 is turned on and the remaining first input The switches SW12 to SW1n and SWn + 1 and the second input switches SW21 to SW2n are both turned off. Accordingly, the integrating unit A1 of the first sensing channel CH1 integrates the input current from the current source 230 and outputs it as a sensing voltage through the sampling / holder SH1, so that the characteristic of the first sensing channel CH1 And outputs the first channel sensing value. At the same time, the current integrator A2 and the sampling / holder SH2 of the second sensing channel CH2, which are adjacent to the first sensing channel CH1 and are not connected to the current source 230, output the noise- And outputs it as a sensing value. Therefore, the noise removing unit 224 removes the sampling / holder SH1 of the second sensing channel CH1 from the first channel sensing value supplied from the sampling / holder SH1 of the first sensing channel CH1 through the MUX1 223, And outputs the first channel sensing value to the ADC 226. The ADC 226 outputs the first channel information to the timing controller 300, Output.

When sensing the second sensing channel CH2, only the first input switch SW12 of the second sensing channel CH2 is turned on and the remaining first input switches SW11, SW13 to SW1n, SWn + 1 and , The second input switches SW21 to SW2n are all turned off. Accordingly, the integrating unit A2 of the second sensing channel integrates the input current from the current source 230 and outputs a second channel sensing value according to the characteristics of the second sensing channel (CH2) through the sampling / holder SH2 The current integrator A3 and the sampling / holder SH3 of the third sensing channel CH3 which are adjacent to the second sensing channel CH2 and are not connected to the current source 230 output the noise generated by the noise to the noise And outputs it as a sensing value. Therefore, the noise removing unit 224 removes the sampling / holder (SH3) of the third sensing channel (CH3) from the second channel sensing value supplied from the sampling / holder (SH2) of the second sensing channel And outputs the first channel sensing value to the ADC 226. The ADC 226 outputs the first channel sensing information to the timing controller 300, Output.

Likewise, the remaining sensing channels CH3 to CHn sequentially sense the input current, sense noise through the adjacent channel, and sequentially output the noise-removed channel sensing values. The channel sensing value of the last sensing channel CHn is subtracted from the noise sensed from the dummy sensing channel CHn + 1, thereby outputting the n-th channel sensing value from which the noise is removed.

FIG. 6 is an equivalent circuit diagram showing embodiments of the noise removing unit shown in FIG. 5. FIG.

The noise eliminator 224 shown in Fig. 5 performs noise sensing from the actual sensing value Vreal using the capacitor coupling circuit shown in Fig. 6 (a) or the differential amplifier DA shown in Fig. 6 (b) The value (Vnoise) can be deducted.

In the capacitor coupling circuit shown in Fig. 6 (a), the first and second switches SWa and SWb are turned on and the third and fourth switches SWc and SWd are turned off. The actual sensed value Vreal from the MUX1 223 and the noise sensing value Vnoise from the MUX2 225 are supplied to the first and second nodes a and b of the first capacitor Ca, So that the first capacitor Ca charges the difference (Vreal-Vnoise) between the actual sensing value and the noise sensing value, i.e., the noise-removed sensing value.

Then, the first and second switches SWa and SWb are turned off, and the third and fourth switches SWc and SWd are turned on. The voltage Vreal-Vnoise stored in the first capacitor Ca is supplied to the second capacitor Cb to be charged. At this time, the reference voltage Vref is applied to the second node d of the second capacitor Cb. . Accordingly, the voltage of the first node c of the second capacitor Cb becomes Vreal-Vnoise + Vref, and the second capacitor Cb charges and outputs the noise-removed sensing value Vreal-Vnoise.

The differential amplifier DA shown in Fig. 6 (b) differs from the noise sensing value Vnoise from the MUX2 225 by the difference between the actual sensing value Vreal from the MUX1 223 and the noise sensing value Vnoise Vreal-Vnoise = Vout).

7 is a graph showing sensing data of each channel by the current sensing device of the OLED display according to the present invention.

7 is a graph illustrating the relationship between the actual sensing value Real for each channel sensed in the calibration process of the sensing unit 220 using the current source 230 and the noise sensing value Noise of the adjacent channel, (W / Noise) obtained by subtracting the noise sensing value (Noise) from the sensing data (100, 20, 60). Referring to FIG. 7, it can be seen that the sensing data 100, 20 and 60 from which the noise sensing value (Noise) is subtracted from the actual sensing value Real (w / Noise) noise can be obtained.

FIG. 8 is a graph illustrating a noise removing effect of the current sensing device of the OLED display device according to the present invention in comparison with the conventional art.

FIG. 8A shows a sensing code for each channel in which noises are removed in FIG. 7, and it can be seen that the sensing data 100, 20, and 600 are constant.

8 (b) and 8 (c) are graphs showing the relationship between the sensed input current (ideal sensing code) and the output current (real sensing code) in the calibration process of the sensing unit 220 using the current source 230, Fig. 8 (b) shows the graph before noise removal, and Fig. 8 (c) shows the result after noise removal. 8 (b) shows that the slope of the graph of the output current (Real Sensing Code) versus the input current (Ideal Sensing Code) is irregular and irregular due to a noise component introduced in the calibration process of the sensing unit 220, Is obtained by stably extracting the offset / gain of the sensing unit 220 from the noise-removed sensing data by eliminating the noise from the sensed data and keeping the slope of the graph of the output current (Real Sensing Code) It can be seen that

As described above, the current sensing method and apparatus of the OLED display according to the present invention sense the output current for each channel in the calibration process of the sensing unit using the current source, sense noise through the adjacent sensing channel, The accurate offset and gain can be extracted and stored from the noise-removed channel sensing value.

Therefore, the current sensing method and apparatus of the OLED display according to the present invention compensates the sensing data (pixel information) by reflecting the correct offset and gain when sensing the pixel current, and from the sensing data (pixel information) By extracting and storing the compensation value according to the characteristic, the uneven brightness can be compensated by using the stored compensation value.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of illustration, Can be carried out within a range. Accordingly, such modifications are deemed to be within the scope of the present invention, and the scope of the present invention should be determined by the following claims.

100: display panel 200: data driver
210: Data supply unit 220:
230: current source 300: timing controller
310: offset / gain extracting unit 320: compensation value extracting unit
330: Data processing unit 340: Control signal generating unit
400: memory 410: LUT1
420: LUT2 211: Shift register
212: first latch portion 213: second latch portion
214: DAC unit 215: gamma voltage generator
216: Output buffer unit 222: Current-voltage conversion unit
224: Noise removing unit 226: ADC
223: MUX1 225: MUX2

Claims (10)

A display panel including a plurality of sub-pixels,
A data supplying section for supplying a data signal to each sub pixel of the display panel; a sensing section for sensing the pixel current of each driven sub pixel to output pixel information; A driver,
The sensing unit senses an output according to characteristics of the sensing channels of the sensing unit using the current source, senses noise through an adjacent sensing channel, senses noise from the sensed channel outputs, (Hereinafter referred to as " OLED ") display device. The method according to claim 1,
Further comprising a timing controller connected to the data driver,
The timing controller
(LUT1) that compares the channel information supplied from the sensing unit with the input current information of the current source to extract an offset and a gain for compensating for a difference in the characteristics of the sensing channels, and stores the offset and gain in a first look- / Gain extraction unit,
A compensation value extracting unit for correcting the pixel information supplied from the sensing unit using the offset and gain from the LUT 1, extracting a compensation value according to the characteristics of each subpixel from the corrected pixel information,
And a data processing unit for compensating data to be supplied to the respective sub-pixels using the compensation value from the LUT 2 and outputting the compensated data to the data driver. The method according to claim 1,
The sensing unit
A current-to-voltage converter for converting the input current supplied from the current source or the display panel into a sensing voltage through integration on a channel basis,
A noise rejection unit for subtracting the noise sensed from the adjacent channel from the sensing voltage of each channel of the current-voltage conversion unit using the current source to output a channel sensing value;
An analog-digital converter converting the pixel sensing value obtained by sensing the pixel current from the display panel through the channel sensing value supplied from the noise removing unit or the current-voltage converter into digital data and outputting the digital signal as channel information or pixel information Converter (hereinafter referred to as " ADC "). The method of claim 3,
The current-voltage converter
And a plurality of sensing channels connected to the plurality of sensing lines of the display panel and connected in common to the current source,
Each of the plurality of sensing channels
A first input switch connected to the current source,
A second input switch connected to any one of the plurality of sensing lines,
A current integrator connected to the first and second input switches for integrating an input current supplied through the first or second input switch and outputting the integrated current as the sensing voltage;
And a sampling and holder for sampling and holding the sensing voltage from the current integrator and outputting the same,
The sensing unit
A first multiplexer for selecting one of the plurality of sensing channels and selecting the sensing voltage from the selected sensing channel and outputting the sensing voltage to the noise removing unit;
Further comprising a second multiplexer for selecting an output of a sensing channel adjacent to the selected sensing channel and outputting the sensed noise from the adjacent channel to the noise removing unit,
Wherein the noise eliminating unit subtracts the noise from the second multiplexer from the sensing voltage from the first multiplexer and outputs the result as the channel sensing value. The method of claim 4,
The current-voltage converter
And a dummy sensing channel disposed adjacent to the first or the last sensing channel among the plurality of sensing channels and adjacent to the first or the last sensing channel for the noise sensing. In claim 4 or claim 5
Wherein the plurality of sensing channels sequentially integrate an input current from the current source to output the sensing voltage, and each time the sensing voltage is output, a sensing channel adjacent to the sensing channel outputs an output To the noise. Sensing outputs of the sensing units according to characteristics of the sensing channels using a current source,
Sensing an output of an adjacent sensing channel as noise each time the output of the sensing channel is sensed for each channel;
And subtracting noise from the adjacent sensing channel from the output of the sensing channel to output as channel information. The method of claim 7,
Comparing the channel information with input current information of the current source to extract an offset and a gain for compensating for a difference in characteristics of the sensing channels and storing the offset and gain in the LUT1;
Driving the subpixels of the display panel, sensing the pixel current supplied from the driven subpixel in the sensing unit and outputting the sensed pixel information,
Further comprising the steps of: correcting the pixel information using an offset and a gain from the LUT1, extracting compensation values according to characteristics of the respective subpixels from the corrected pixel information, and storing the compensation values in the LUT2, Way. The method of claim 7,
Sensing the output of the sensing channel includes sequentially inputting an input current supplied from the current source and integrating the input current for each sensing channel to output a sensing voltage,
Wherein the step of sensing the noise includes outputting an output generated without the input current from the sensing channel adjacent to the sensing channel to the noise each time the sensing voltage is output from the sensing channel, Sensing method. The method of claim 9,
Wherein the sensing voltage of the first or the last sensing channel among the plurality of sensing channels is calculated by subtracting the sensed noise from the dummy sensing channel adjacent to the first or last sensing channel.

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