KR101557289B1 - Light emitting diode display device and driving method thereof - Google Patents

Abstract

The present invention relates to a light emitting diode display device and a driving method thereof that can improve brightness and image quality by compensating for deterioration of characteristics of a light emitting device.

A light emitting diode display device according to the present invention includes a plurality of pixels formed in regions defined by intersections of a plurality of data lines and a plurality of scan lines, A source terminal connected to the jth data line among the plurality of data lines, and a drain terminal connected to the first node; A driving transistor including a gate terminal connected to the first node and a drain terminal connected to the driving power supply; A light emitting element connected to a source terminal of the driving transistor and a ground power source and emitting light by a current supplied from the driving transistor; A capacitor connected to the first node and a source terminal of the driving transistor; A first switching element having a gate terminal connected to the (i + 1) th scan line among the plurality of scan lines, a source terminal connected to the first node, and a drain terminal connected to the second node; A second switching element having a gate terminal and a source terminal connected in a diode form to the second node, and a drain terminal connected to the third node; A third switching element having a gate terminal connected to the third node, a source terminal connected to the second node, and a drain terminal connected to the driving power source; And a fourth switching element having a gate terminal connected to the (i + 1) th scanning line, a source terminal connected to the third node, and a drain terminal connected to the driving power source.

According to the present invention, the gate voltage of the driving transistor is controlled according to the amount of light emitted from the light emitting device to compensate for the amount of light emitted from the light emitting device, thereby preventing a decrease in luminance and a decrease in luminous efficiency due to deterioration of the light emitting device .

Light emitting diode display, pixel, light emitting element, deterioration, light quantity, compensation

Description

TECHNICAL FIELD [0001] The present invention relates to a light emitting diode (LED)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode display device, and more particularly, to a light emitting diode display device and a method of driving the same, which can improve luminance and image quality by compensating for characteristic deterioration of a light emitting device.

Currently, various flat panel display devices capable of reducing weight and volume, which are disadvantages of cathode ray tubes (CRTs), are being developed. A flat panel display device includes a liquid crystal display (LCD), a field emission display, a plasma display panel (PDP), and a light emitting diode (PDP) display device.

Among the flat panel display devices, a light emitting diode display device is a self-luminous device that emits a fluorescent material by recombination of electrons and holes. In comparison with a passive light emitting device requiring a separate light source like a liquid crystal display device, It has the advantage of being as fast as the same level.

2. Description of the Related Art In general, a light emitting diode display device is a display device that emits light by electrically exciting a fluorescent material, and is classified into an inorganic light emitting diode display device and an organic light emitting diode display device according to its material and structure. The light emitting diode display device may be classified into a passive matrix type and an active matrix type depending on the arrangement of pixels formed on the display panel.

1 is a circuit diagram schematically showing pixels of a general LED display device.

Referring to FIG. 1, a pixel of a typical light emitting diode display device includes a switching transistor ST, a driving transistor DT, a capacitor CST, and a light emitting device OLED.

The switching transistor ST is switched in accordance with a scanning signal supplied to the scanning line SL to supply the driving transistor DT with the data voltage VData supplied to the data line DL.

The driving transistor DT is switched in accordance with the data voltage VData supplied from the switching transistor ST to control a current flowing from the driving power supply VDD to the light emitting element OLED.

The capacitor CST is connected between the gate terminal of the driving transistor DT and the ground line VL and stores a voltage corresponding to the data voltage VData supplied to the gate terminal of the driving transistor DT, And keeps the turn-on state of the transistor DT constant for one frame.

The light emitting device OLED is electrically connected between the source terminal of the driving transistor DT and the ground power supply VSS and emits light by the data current supplied from the driving transistor DT. At this time, the current i flowing in the light emitting element OLED is changed according to the voltage Vgs between the gate and source of the driving transistor DT, the threshold voltage Vth of the driving transistor DT, and the data voltage VData .

The pixel of such a general LED display device controls the magnitude of the data current i flowing from the driving power source VDD to the light emitting element OLED by switching the driving transistor DT according to the data voltage VData, And a predetermined image is displayed by causing the element OLED to emit light.

However, in a general LED display device, the threshold voltage of the driving transistor DT increases according to driving for a long time or the current i flowing in the light emitting device OLED varies due to deterioration of characteristics of the light emitting device OLED, And image quality can not be obtained.

In order to solve the above problems, a pixel of a typical light emitting diode display device may further include a voltage compensation circuit.

The voltage compensation circuit compensates the threshold voltage of the driving transistor DT so that the current i flowing through the light emitting element OLED is determined only by the data voltage regardless of the threshold voltage of the driving transistor DT.

However, although the voltage compensation circuit can compensate the threshold voltage of the driving transistor DT, there is a problem that the degradation of the characteristics of the light emitting device OLED can not be compensated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a light emitting diode display device and a method of driving the same, which can improve brightness and image quality by compensating for characteristic deterioration of a light emitting device.

According to an aspect of the present invention, there is provided a light emitting diode display device including a plurality of pixels formed in regions defined by intersections of a plurality of data lines and a plurality of scan lines, a switching transistor having a gate terminal connected to the ith scan line, a source terminal connected to the jth data line among the plurality of data lines, and a drain terminal connected to the first node; A driving transistor including a gate terminal connected to the first node and a drain terminal connected to the driving power supply; A light emitting element connected to a source terminal of the driving transistor and a ground power source and emitting light by a current supplied from the driving transistor; A capacitor connected to the first node and a source terminal of the driving transistor; A first switching element having a gate terminal connected to the (i + 1) th scan line among the plurality of scan lines, a source terminal connected to the first node, and a drain terminal connected to the second node; A second switching element having a gate terminal and a source terminal connected in a diode form to the second node, and a drain terminal connected to the third node; A third switching element having a gate terminal connected to the third node, a source terminal connected to the second node, and a drain terminal connected to the driving power source; And a fourth switching element having a gate terminal connected to the (i + 1) th scanning line, a source terminal connected to the third node, and a drain terminal connected to the driving power source.

According to an aspect of the present invention, there is provided a light emitting diode display device including a plurality of pixels formed in regions defined by intersections of a plurality of data lines and a plurality of scan lines, A light emitting element for emitting light; A switching transistor for supplying a data voltage supplied from a jth data line among a plurality of data lines to a first node in accordance with an i-th scan signal supplied from an i-th scan line among a plurality of scan lines; A driving transistor for controlling a current flowing from the driving power source to the light emitting element according to the voltage of the first node; A capacitor for maintaining a voltage between a gate terminal and a source terminal of the driving transistor for a predetermined period; And an amount of light emitted from the light emitting element in accordance with an (i + 1) -th scanning signal supplied from the (i + 1) -th scanning line of the plurality of scanning lines connected between the first node and the driving power supply, And an optical compensator for controlling the voltage.

Wherein the light compensating unit generates a compensation voltage inversely proportional to an amount of light emitted from the light emitting device according to the (i + 1) th scanning signal using the driving power source and supplies the compensation voltage to a second node; And a first switching element connected between the first node and the second node and supplying a compensation voltage of the second node to the first node according to the (i + 1) th scan signal. do.

According to an aspect of the present invention, there is provided a method of driving a light emitting diode display including a plurality of pixels formed in regions defined by intersections of a plurality of data lines and a plurality of scan lines, The method comprising: turning on a switching transistor according to an i-th scan signal supplied from an i-th scan line among a plurality of scan lines to supply a data voltage supplied from a j-th data line among a plurality of data lines to a first node step; Turning on a driving transistor according to the data voltage supplied to the first node and supplying a current corresponding to the data voltage to the light emitting element to emit light; And an optical compensator connected between the first node and the driving power source to detect an amount of light emitted from the light emitting element according to an (i + 1) -th scan signal supplied from an (i + 1) And controlling a voltage of the first node according to a light amount of the light emitting element to compensate for an amount of light emitted from the light emitting element.

The step of compensating the amount of light emitted from the light emitting device may include generating a photocurrent corresponding to an amount of light emitted from the light emitting device in accordance with the (i + 1) th scan signal. Generating a compensation voltage corresponding to the photocurrent; Supplying the compensation voltage to the first node according to the (i + 1) th scanning signal; And compensating an amount of light emitted from the light emitting device by controlling an amount of current supplied to the light emitting device according to the compensation voltage supplied to the first node.

The driving method of the light emitting diode display device may further include storing a voltage corresponding to a voltage of the first node controlled by a light amount of the light emitting element in a capacitor connected between a gate terminal and a source terminal of the driving transistor, And maintaining the voltage between the gate terminal and the source terminal of the driving transistor for a predetermined period of time using the stored voltage.

As described above, according to the present invention, by using the optical compensator connected between the gate terminal of the driving transistor and the driving power source, the gate voltage of the driving transistor is controlled according to the amount of light emitted from the light emitting element, It is possible to prevent degradation of luminance and decrease in luminous efficiency due to deterioration of the driving transistor and / or deterioration of the light emitting element.

According to another aspect of the present invention, there is provided a method of driving a light emitting device, comprising: amplifying a photocurrent according to an amount of light emitted from a light emitting device to generate a compensation voltage to control a gate voltage of the driving transistor to compensate an amount of light emitted from the light emitting device, The reduction of the aperture ratio of the pixel due to the optical compensating portion can be minimized.

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

2 is a schematic view for explaining a light emitting diode display device according to an embodiment of the present invention.

2, a light emitting diode display device according to an embodiment of the present invention includes a display panel 100 including a plurality of pixels P, a data driver 200 for supplying a data voltage to each pixel P, And a scan driver 300 for supplying a scan signal to each pixel P.

Each of the plurality of pixels P is formed for each region defined by the intersection of n (where n is a natural number) data lines DL1 to DLn and m (m is a natural number) scanning lines SL1 to SLm) do. In this case, the pixel P is turned on in response to the i-th scan signal supplied to the i-th scan line of the m-th scan line (where i is any one of the first to m-th scan lines) , j is a natural number of any one of the first to the nth) data lines to emit a light emitting element according to a data current corresponding to a data voltage supplied to the plurality of scan lines SL1 to SLm, The amount of light emitted from the light emitting element is compensated according to the amount of light emitted from the light emitting element in accordance with the (i + 1) th scan signal supplied to the (i + 1) th scan line. A detailed description of such a pixel P will be described later.

The data driver 200 receives n data signals corresponding to the number of the data lines DL1 to DLn on a horizontal period basis to generate n data voltages corresponding to n data signals, To each of the n data lines DL1 to DLn.

The scan driver 300 generates scan signals for sequentially driving the m scan lines SL1 to SLm and sequentially supplies the generated scan signals to the m main scan lines SL1 to SLm in units of horizontal periods do.

3 is a circuit diagram illustrating a pixel of a light emitting diode display device according to an embodiment of the present invention.

3, the pixel P of the light emitting diode display according to the exemplary embodiment of the present invention includes a light emitting device OLED, a switching transistor ST, a driving transistor DT, a capacitor Cst, (110).

The light emitting device OLED includes an anode terminal connected to the driving transistor DT, a cathode terminal connected to the ground power source VSS, and a light emitting layer formed to include a fluorescent material between the anode terminal and the cathode terminal. The light emitting device OLED emits light by electrically exciting the fluorescent material according to the current flowing from the anode terminal to the cathode terminal.

The switching transistor ST includes a gate terminal connected to the i-th scan line SLi, a source terminal connected to the j-th data line DLj, and a drain terminal connected to the first node N1. Here, the switching transistor ST may be formed of an NMOS type thin film transistor. The switching transistor ST is turned on by the i-th scan signal supplied to the i-th scan line SLi to supply the data voltage supplied to the j-th data line DLj to the first node N1 .

The driving transistor DT includes a gate terminal connected to the first node N1, a drain terminal connected to the driving power supply VDD and a source terminal connected to the anode terminal of the light emitting element OLED. Here, the driving transistor DT may be formed of an NMOS type thin film transistor. The driving transistor DT is turned on by the data voltage supplied to the first node N1 to control the current flowing from the driving power supply VDD to the light emitting element OLED.

The driving transistor DT controls the current flowing from the driving power supply VDD to the light emitting element OLED according to the compensation voltage supplied from the light compensating unit 110 according to the amount of light emitted from the light emitting element OLED.

The capacitor Cst is a two-terminal element and has a first terminal connected to the first node N1 and a second terminal commonly connected to the source terminal of the driving transistor DT and the anode terminal of the light emitting element OLED . The capacitor Cst maintains the voltage between the gate terminal and the source terminal of the driving transistor DT for a predetermined period (for example, one frame).

The light compensating unit 110 is connected between the first node N1 and the driving power source VDD and is connected to the light emitting device OLED according to the (i + 1) th scan signal supplied to the (i + And controls the voltage of the first node N1 to compensate for the amount of light emitted from the light emitting device OLED to compensate for the luminance degradation due to deterioration of the light emitting device OLED.

To this end, the optical compensation unit 110 generates a compensation voltage in inverse proportion to the amount of light emitted from the light emitting device OLED according to the (i + 1) th scan signal using the driving power supply VDD and supplies the compensation voltage to the second node A voltage generating unit 112; And a first switching element T1 for supplying a compensation voltage of the second node N2 to the first node N1 in accordance with the (i + 1) th scan signal.

The first switching element T1 has a gate terminal connected to the (i + 1) th scanning line SLi + 1, a source terminal connected to the first node N1, and a drain terminal connected to the second node N2 . Here, the first switching device T1 may be an NMOS type thin film transistor. The first switching element T1 is turned on by the (i + 1) th scan signal and supplies the compensation voltage of the second node N2 to the first node N1 so that the voltage on the first node N1 And is controlled in accordance with the amount of light emitted from the light emitting device OLED.

The compensation voltage generating unit 112 includes the second to fourth switching elements T2, T3 and T4.

The second switching element T2 is an optical detection transistor connected in a diode form to the second node N2 and has a gate terminal and a source terminal connected to the second node N2 and a drain terminal connected to the third node N2. . Here, the second switching device T2 may be an NMOS type thin film transistor. As shown in FIG. 4, the second switching device T2 generates a photocurrent corresponding to the amount of light emitted when the light emitting device OLED emits according to the photocurrent characteristic according to the amount of incident light. At this time, the photocurrent generated by the second switching device T2 increases when the amount of light emitted when the light emitting device OLED emits is large (A), when the amount of light emitted when the light emitting device OLED emits light is small (B).

The second switching device T2 generates a photocurrent according to the amount of light emitted from the light emitting device OLED to adjust the voltage of the third node N3. That is, the second switching element T2 functions as a resistor between the second node N2 and the third node N3 in a circuit, and when the photocurrent decreases, the voltage of the third node N3 While decreasing the voltage of the third node N3 by an increasing photocurrent when the photocurrent increases.

The third switching device T3 is configured to include a gate terminal connected to the third node N3, a source terminal connected to the second node N2, and a drain terminal connected to the driving power supply VDD. At this time, the third switching device T3 is formed to be relatively larger than the channel width / channel length of the second switching device T2, thereby amplifying the photocurrent generated in the second switching device T2 . Here, the third switching device T3 may be an NMOS type thin film transistor.

The third switching element T3 is switched according to the voltage of the third node N3 controlled by the photocurrent generated by the second switching element T2 so that the driving voltage VDD is applied to the second node N2 To amplify the photocurrent generated by the second switching device T2 to generate a compensation voltage that is inversely proportional to the amount of light emitted from the light emitting device OLED.

The fourth switching device T4 includes a gate terminal connected to the (i + 1) th scanning line SLi + 1, a source terminal connected to the third node N3, and a drain terminal connected to the driving power supply VDD . Here, the fourth switching device T4 may be formed of an NMOS type thin film transistor. The fourth switching element T4 is turned on by the (i + 1) th scanning signal SLi + 1 to supply the bias voltage by the driving power source VDD to the third node N3, (T3).

FIG. 5 is a waveform chart showing a driving timing for the pixel shown in FIG. 3, FIG. 6 is a view for explaining driving of a pixel by the i.sup.th scanning signal shown in FIG. 5, And the driving of the pixel by the (i + 1) th scanning signal.

A method of driving a pixel in a method of driving a light emitting diode display according to an embodiment of the present invention will now be described with reference to FIGS. 5 to 7. FIG.

First, an i-th scan signal SSi in a high state is supplied to an i-th scan line SLi and a data voltage is supplied to a j-th data line DLj. As shown in FIG. 6, The switching transistor ST is turned on by the i-th scanning signal SSi in the state and the data voltage is supplied to the first node N1 so that the driving transistor DT is driven by the data voltage of the first node N1 And the current (i) corresponding to the data voltage is supplied to the light emitting element OLED. Accordingly, the light emitting element OLED emits the predetermined light by the current i supplied from the driving transistor DT.

Then, the i-th scan signal SSi supplied to the i-th scan line SLi becomes low and the (i + 1) -th scan signal SSi + 1 of the high- The switching transistor ST is turned off by the i-th scan signal SSi in the low state, and the (i + 1) -th scan signal SSi + The first and fourth switching elements T1 and T4 of the voltage compensating unit 110 are turned on at the same time. When the first and fourth switching devices T1 and T4 are turned on, a photocurrent corresponding to the amount of light emitted from the light emitting device OLED is generated by the second switching device T2, The voltage of the third node N3 is adjusted to turn on the third switching device T3 so that the compensation voltage generated by the amplification of the third switching device T3 is applied to the second node N2, And is supplied to the first node N1 through the element T1. When the compensation voltage is supplied to the first node N1, the driving transistor DT controls the current i flowing through the light emitting element OLED to correspond to the compensation voltage supplied to the first node N1, OLED). ≪ / RTI >

8, the gate voltage of the driving transistor DT varies with the level of the data voltage in the data writing period by the i-th scanning signal SSi, and the gate voltage of the i + The level of the compensation voltage according to the amount of light emitted from the light emitting device OLED varies in the optical compensation period section due to the first scanning signal SSi + 1, and the level of the compensation voltage is maintained in the emission sustaining interval by the capacitor Cst . The gate voltage level of the driving transistor DT in the light compensation period is lowered when the amount of light emitted when the light emitting device OLED emits is larger than when the light emitting amount of the light emitting device OLED is less (B).

Meanwhile, in a case where the amount of light emitted from the light emitting device OLED decreases due to the deterioration of the driving transistor DT, the light amount compensation process of the light emitting device OLED according to the present invention will be described briefly.

When the amount of light emitted from the light emitting device OLED is reduced, the photocurrent generated by the second switching device T2 is reduced. Accordingly, the third node N3, that is, the gate of the third switching device T3 As the voltage increases, the amount of current flowing from the driving power supply VDD to the second node N2 through the third switching element T3 increases.

The gate voltage of the driving transistor DT rises due to the increase in the amount of current flowing to the second node N2 by the third switching element T3 so that the driving current flows from the driving power supply VDD through the driving transistor DT to the light emitting element The amount of current flowing to the OLED increases and the amount of light emitted from the OLED increases.

The light emitting diode display device and the driving method thereof according to the embodiment of the present invention as described above include the optical compensator 110 connected between the gate terminal (first node) of the driving transistor DT and the driving power supply VDD The gate voltage of the driving transistor DT is controlled according to the amount of light emitted from the light emitting device OLED to compensate the amount of light emitted from the light emitting device OLED, Can be prevented.

In addition, the present invention generates the compensation voltage by amplifying the photocurrent generated in the second switching device T2 using the third switching device T3, thereby generating the compensation voltage regardless of the size of the second switching device T2. It is possible to minimize the aperture ratio of the pixel P by the optical compensator 110 because the size of the second switching element T2 can be reduced as well as the optical current according to the amount of light emitted from the OLED have.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present invention. .

1 is a circuit diagram schematically showing pixels of a general LED display device.

2 is a schematic view for explaining a light emitting diode display device according to an embodiment of the present invention.

3 is a circuit diagram illustrating a pixel of a light emitting diode display device according to an embodiment of the present invention.

4 is a graph showing the photocurrent characteristic of the second switching device shown in FIG.

5 is a waveform diagram showing a driving timing for the pixel shown in Fig.

FIG. 6 is a diagram for explaining driving of a pixel by the i-th scan signal shown in FIG.

FIG. 7 is a diagram for explaining pixel driving by the (i + 1) th scan signal shown in FIG.

FIG. 8 is a diagram showing a variation in the gate voltage of the driving transistor according to the driving timing for the pixel shown in FIG. 5; FIG.

Description of the Related Art [0002]

100: display panel 110:

112: compensation voltage generator 200:

300:

Claims (10)

And a plurality of pixels formed for each region defined by the intersection of the plurality of data lines and the plurality of scan lines, The pixel includes: A switching transistor having a gate terminal connected to the i < th > scan line among the plurality of scan lines, a source terminal connected to the jth data line among the plurality of data lines, and a drain terminal connected to the first node; A driving transistor including a gate terminal connected to the first node and a drain terminal connected to the driving power supply; A light emitting element connected to a source terminal of the driving transistor and a ground power source and emitting light by a current supplied from the driving transistor; A capacitor connected to the first node and a source terminal of the driving transistor; A first switching element having a gate terminal connected to the (i + 1) th scan line among the plurality of scan lines, a source terminal connected to the first node, and a drain terminal connected to the second node; A second switching element having a gate terminal and a source terminal connected in a diode form to the second node, and a drain terminal connected to the third node; A third switching element having a gate terminal connected to the third node, a source terminal connected to the second node, and a drain terminal connected to the driving power source; And And a fourth switching element having a gate terminal connected to the (i + 1) th scanning line, a source terminal connected to the third node, and a drain terminal connected to the driving power source. Device. And a plurality of pixels formed for each region defined by the intersection of the plurality of data lines and the plurality of scan lines, The pixel includes: A light emitting element emitting light by a supplied current; A switching transistor for supplying a data voltage supplied from a jth data line among a plurality of data lines to a first node in accordance with an i-th scan signal supplied from an i-th scan line among a plurality of scan lines; A driving transistor for controlling a current flowing from the driving power source to the light emitting element according to the voltage of the first node; A capacitor for maintaining a voltage between a gate terminal and a source terminal of the driving transistor for a predetermined period; And (I + 1) -th scan signal supplied from the i + 1 < th > scan line of the plurality of scan lines connected between the first node and the driving power supply, detects the amount of light emitted from the light emitting element, And an optical compensator for controlling the light emitting diode. 3. The method of claim 2, Wherein the optical compensator comprises: A compensation voltage generator for generating a compensation voltage inversely proportional to an amount of light emitted from the light emitting element according to the (i + 1) th scanning signal using the driving power source and supplying the compensation voltage to a second node; And And a first switching element connected between the first node and the second node and supplying a compensation voltage of the second node to the first node according to the (i + 1) th scan signal. Light emitting diode display. The method of claim 3, Wherein the compensation voltage generator comprises: A gate terminal and a source terminal are connected in a diode form to the second node and a drain terminal is connected to a third node to generate a photocurrent corresponding to an amount of light emitted from the light emitting device to control the voltage of the third node A second switching element; A third switching device connected between the second node and the driving power supply to generate the compensation voltage according to the voltage of the third node and supply the generated compensation voltage to the second node; And And a fourth switching element connected between the driving power source and the third node and supplying a bias voltage to the third node according to the (i + 1) th scanning signal to control switching of the third switching element And the light-emitting diode display device. The method according to claim 1 or 4, Wherein the third switching element amplifies a photocurrent generated in the second switching element to generate the compensation voltage inversely proportional to an amount of light emitted from the light emitting element. 6. The method of claim 5, Wherein a size of the third switching device according to a channel width / channel length is relatively larger than that of the second switching device. A driving method of a light emitting diode display device including a plurality of pixels formed in regions defined by intersections of a plurality of data lines and a plurality of scanning lines, Turning on a switching transistor according to an i-th scan signal supplied from an i-th scan line among a plurality of scan lines to supply a data voltage supplied from a j-th data line among the plurality of data lines to a first node; Turning on a driving transistor according to the data voltage supplied to the first node and supplying a current corresponding to the data voltage to the light emitting element to emit light; And (I + 1) -th scan line supplied from an i + 1 < th > scan line among a plurality of pixels using an optical compensator connected between the first node and a driving power source, And controlling a voltage of the first node according to an amount of light of the light emitting device to compensate for an amount of light emitted from the light emitting device. 8. The method of claim 7, The step of compensating the amount of light emitted from the light emitting device includes: Generating a photocurrent corresponding to an amount of light emitted from the light emitting device according to the (i + 1) th scanning signal; Generating a compensation voltage corresponding to the photocurrent; Supplying the compensation voltage to the first node according to the (i + 1) th scanning signal; And And compensating an amount of light emitted from the light emitting device by controlling an amount of current supplied to the light emitting device according to the compensation voltage supplied to the first node. 8. The method of claim 7, A voltage corresponding to a voltage of the first node controlled according to a light amount of the light emitting element is stored in a capacitor connected between a gate terminal and a source terminal of the driving transistor after the step of compensating an amount of light emitted from the light emitting element And maintaining a voltage between a gate terminal and a source terminal of the driving transistor for a predetermined period by using a voltage stored in the capacitor. 9. The method of claim 8, Wherein the step of generating the compensation voltage amplifies the photo current to generate the compensation voltage in inverse proportion to the amount of light emitted from the light emitting device.

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