KR100613089B1 - Pixel and Light Emitting Display Using The Same - Google Patents

Abstract

The present invention relates to a pixel capable of displaying an image of desired luminance.

According to an exemplary embodiment of the present invention, a pixel includes a light emitting device, a first transistor configured to repeat turn-on and turn-off at least once in a specific horizontal period in response to a first scan signal supplied from a first scan line, and a first transistor supplied from a second scan line A second transistor for maintaining a turn-on state for the specific horizontal period in response to a two-scan signal, and a pixel current corresponding to a data signal supplied from a data line via the first transistor, to the light emitting element; It has a drive part.

With this arrangement, the present invention can display an image of desired luminance.

Description

Pixel and Light Emitting Display Using The Same}             

1 illustrates a conventional light emitting display device.

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

FIG. 3 is a diagram illustrating a first embodiment of the pixel illustrated in FIG. 2.

4 is a waveform diagram illustrating a method of driving the pixel illustrated in FIG. 3.

FIG. 5 is a block diagram illustrating an embodiment of a data integrated circuit shown in FIG. 2.

FIG. 6 is a block diagram illustrating another embodiment of the data integrated circuit shown in FIG. 2.

FIG. 7 is a detailed diagram illustrating the current adjuster and the selector illustrated in FIG. 5.

FIG. 8 is a diagram illustrating a selection signal supplied to the selection unit illustrated in FIG. 7.

FIG. 9 is a circuit diagram illustrating in detail the current controller illustrated in FIG. 7.

FIG. 10 is a circuit diagram illustrating in detail the comparison unit illustrated in FIG. 7.

FIG. 11 is a diagram illustrating a second embodiment of the pixel illustrated in FIG. 2.

12 is a waveform diagram illustrating a driving method of the pixel illustrated in FIG. 11.

FIG. 13 is a diagram illustrating a third embodiment of the pixel illustrated in FIG. 2.

FIG. 14 is a diagram illustrating a fourth embodiment of the pixel illustrated in FIG. 2.

<Explanation of symbols for the main parts of the drawings>

10,110: scan driver 20,120: data driver

30,130: image display unit 40,140: pixel

50,150: timing controller 129: data integrated circuit

142: drive unit 200: shift register unit

210: sampling latch portion 220: holding latch portion

230: current digital-analog converter 240: current control block

242: comparison unit 244: current control unit

250: selection block 260: level shifter

The present invention relates to a pixel and a light emitting display device using the same, and more particularly, to a pixel and a light emitting display device using the same to display an image of a desired brightness.

Recently, various flat panel displays have been developed to reduce weight and volume, which are disadvantages of cathode ray tubes. The flat panel display includes a liquid crystal display, a field emission display, a plasma display panel, a light emitting display, and the like.

Among the flat panel display devices, the light emitting display device is a self-light emitting device that generates light by recombination of electrons and holes. Such a light emitting display device has an advantage in that it has a fast response speed and is driven with low power consumption. In general, a light emitting display device emits light from a light emitting device by supplying a current corresponding to the data signal to the light emitting device using a transistor formed for each pixel.

1 illustrates a conventional light emitting display device.

Referring to FIG. 1, a conventional light emitting display device includes an image display unit 30 including pixels 40 formed in an area partitioned by scan lines S1 to Sn and data lines D1 to Dm; Controlling the scan driver 10 for driving the scan lines S1 to Sn, the data driver 20 for driving the data lines D1 to Dm, the scan driver 10 and the data driver 20 The timing control part 50 is provided.

The timing controller 50 generates a data drive control signal DCS and a scan drive control signal SCS in response to the synchronization signals supplied from the outside. The data drive control signal DCS generated by the timing controller 50 is supplied to the data driver 20, and the scan drive control signal SCS is supplied to the scan driver 10. The timing controller 50 supplies the data Data supplied from the outside to the data driver 20.

The scan driver 10 receives the scan drive control signal SCS from the timing controller 50. The scan driver 10 receiving the scan driving control signal SCS generates a scan signal and sequentially supplies the generated scan signal to the scan lines S1 to Sn.

The data driver 20 receives the data drive control signal DCS from the timing controller 50. The data driver 20 receiving the data driving control signal DCS generates a data signal and supplies the generated data signal to the data lines D1 to Dm in synchronization with the scan signal.

The image display unit 30 receives the first power source VDD and the second power source VSS from the outside and supplies the same to the pixels 40. Each of the pixels 40 supplied with the first power source VDD and the second power source VSS receives a current flowing from the first power source VDD to the second power source VSS via the light emitting element in response to the data signal. The control generates light corresponding to the data signal.

That is, in the conventional light emitting display device, each of the pixels 40 generates light having a predetermined luminance in response to a data signal. However, in the related art, light having a desired luminance may not be generated due to a nonuniform threshold voltage of a transistor included in each of the pixels 40. In the related art, there is no method of measuring and controlling the current flowing in each of the pixels 40 in response to the data signal.

Accordingly, an object of the present invention is to provide a pixel capable of displaying an image having a desired luminance and a light emitting display device using the same.

In order to achieve the above object, the first aspect of the present invention provides a light emitting device and a first transistor for repeating turn-on and turn-off at least once in a specific horizontal period in response to a first scan signal supplied from the first scan line. And a second transistor that is turned on for the specific horizontal period in response to the second scan signal supplied from the second scan line, and a pixel corresponding to the data signal supplied from the data line via the first transistor. A pixel including a driving unit for supplying current to the light emitting device is provided.

Preferably, the first transistor is connected between the data line and the driver and is turned on for a first period of the specific horizontal period, and is turned on and off at least once for a second period except the first period. do. The second transistor is connected between the common terminal of the driving unit and the light emitting device and the data line. And a third transistor connected between the driving unit and the light emitting element and turned off during the specific horizontal period in response to the light emission control signal supplied from the light emission control line, and turned on for the other period.

Hereinafter, preferred embodiments of the present invention may be easily implemented by those skilled in the art with reference to FIGS. 2 to 14 as follows.

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

Referring to FIG. 2, a light emitting display device according to an exemplary embodiment of the present invention includes first scan lines S11 to S1n, second scan lines S21 to S2n, emission control lines E1 to En, and data lines D1 to. The image display unit 130 including the pixels 140 formed in the area partitioned by Dm, the first scan lines S11 to S1n, the second scan lines S21 to S2n, and the emission control lines E1. To En), a data driver 120 for driving the data lines D1 to Dm, a timing controller for controlling the scan driver 110 and the data driver 120 150).

The image display unit 130 is formed in an area partitioned by the first scan lines S11 to S1n, the second scan lines S21 to S2n, the emission control lines E1 to En, and the data lines D1 to Dm. Pixels 140 are provided. The pixels 140 receive a first power source VDD and a second power source VSS from an external source. Each of the pixels 140 supplied with the first power source VDD and the second power source VSS receives a second signal from the first power source VDD via a light emitting element in response to a data signal supplied from the data line D. FIG. The pixel current flowing to the power supply VSS is controlled. The pixels 140 supply the pixel current to the data driver 120 through the data line D during a part of the horizontal period. To this end, each of the pixels 140 may be configured as shown in FIG. 3. The detailed structure of the pixel 140 shown in FIG. 3 will be described later.

The timing controller 150 generates a data drive control signal DCS and a scan drive control signal SCS in response to external synchronization signals. The data driving control signal DCS generated by the timing controller 150 is supplied to the data driver 120, and the scan driving control signal SCS is supplied to the scan driver 110. The timing controller 150 supplies the data Data supplied from the outside to the data driver 120.

The scan driver 110 receives the scan driving control signal SCS from the timing controller 150. The scan driver 110 supplied with the scan driving control signal SCS sequentially supplies the first scan signal to the first scan lines S11 to S1n, and at the same time, the second scan signal to the second scan lines S21 to S2n. Supply sequentially.

As illustrated in FIG. 4, in the scan driver 110, the first transistor M1 included in the pixel 140 is turned on during a first period of a specific horizontal period, and the first transistor M1 is turned on during the second period. M1) supplies a first scan signal to repeat turn-on and turn-off at least once. The scan driver 110 supplies a second scan signal such that the second transistor M2 included in the pixel 140 is turned on for a specific horizontal period. In addition, the scan driver 110 supplies the light emission control signal so that the third transistor M3 is turned off for a specific horizontal period during which the first scan signal and the second scan signal are supplied, and turned on for the other period. Supply. That is, the emission control signal is supplied to overlap with the first scan signal and the second scan signal, and the width thereof is set equal to or wider than the width of the second scan signal.

The data driver 120 receives the data drive control signal DCS from the timing controller 150. The data driver 120 receiving the data driving control signal DCS generates a data signal and supplies the generated data signal to the data lines D1 to Dm. Here, the data driver 120 is configured as a current sink type. In other words, the data driver 120 receives a current corresponding to the gradation current from the pixel 140 as a data signal.

The data driver 120 receives a pixel current from the pixels 140 during a partial period of the second period of each horizontal period, that is, a period in which the first transistor M1 is turned off. Check whether is the current value corresponding to the gradation current. For example, when the gradation current generated corresponding to the number of bits (or gradation value) of the data is 10 mA, the data driver 120 checks whether the pixel current is 10 mA. Here, when the desired current is not supplied from each of the pixels 140, the data driver 120 increases or decreases the current value supplied to the data line D so that a desired current flows from each of the pixels 140. To this end, the data driver 120 includes at least one data integrated circuit 129 including j channels (where j is a natural number). The detailed configuration of the data integrated circuit 129 will be described later.

FIG. 3 is a diagram illustrating a first embodiment of the pixel illustrated in FIG. 2. In FIG. 3, pixels connected to the m-th data line Dm, the n-th first scan line S1n, the n-th second scan line S2n, and the n-th emission control line En are illustrated in FIG. 3. do.

Referring to FIG. 3, the pixel 140 according to the first embodiment of the present invention includes a light emitting device OLED, a first transistor M1, a second transistor M2, a third transistor M3, and a driver 142. ).

The first transistor M1 is connected between the data line Dm and the driver 142 to electrically connect the data line Dm and the driver 142. The first transistor M1 is controlled by the first scan signal supplied to the n-th first scan line S1n.

The second transistor M2 is connected between the driving unit 142 and the common terminal of the light emitting element OLED and the data line Dm to electrically connect the data line Dm and the driving unit 142. The second transistor M2 is controlled by the second scan signal supplied to the n-th second scan line S2n.

The third transistor M3 is connected between the driver 142 and the light emitting device OLED. The third transistor M3 is controlled by the emission control signal supplied from the nth emission control line En. The emission control signal is supplied to overlap the first and second scan signals supplied to the n-th first scan line S1n and the n-th second scan line S2n. The third transistor M3 is turned off when the light emission control signal is supplied and is turned on for the other period.

The driver 142 supplies a pixel current to the second transistor M2 and the third transistor M3 in response to a data signal supplied from the first transistor M1. To this end, the driver 142 includes a capacitor C for charging a voltage corresponding to the data signal, and a fourth transistor M4 for supplying a pixel current corresponding to the voltage charged to the capacitor C. . Here, the structure of the driving unit 142 is not limited to the structure shown in FIG. 3, and may be selected from any of various circuits currently known and used. In addition, in FIG. 3, for convenience of description, the transistors M1 to M4 are illustrated as PMOS conductivity types, but the present invention is not limited thereto.

Referring to FIGS. 3 and 4, the operation of the pixel 140 will be described in detail. First, the first scan signal is supplied to the nth first scan line S1n during a specific horizontal period of one frame and the nth second scan line at the same time. The second scan signal is supplied to S2n.

The second scan signal supplied to the nth second scan line S2n is supplied to the second transistor M2. Then, the second transistor M2 remains turned on for a certain horizontal period.

The first scan signal supplied to the nth first scan line S1n is supplied to the first transistor M1. At this time, the first transistor M1 is turned on during the first period of the specific horizontal period. Since the first transistor M1 and the second transistor M2 are turned on during the first period, currents leading to the data line Dm, the first transistor M1, the driver 142, and the second transistor M2. A pass is formed. Then, a current corresponding to the data signal is supplied from the pixel 140 to the data driver 120. In practice, the data driver 120 receives a current corresponding to the grayscale current from the pixel 140. In this case, a voltage corresponding to the data signal is charged in the capacitor C included in the driver 142. That is, during the first period, the capacitor C is charged to a voltage corresponding to the current (data signal) sinked by the data driver 120.

Thereafter, the first transistor M1 is turned off at least once in the second period. When the first transistor M1 is turned off, the pixel current corresponding to the voltage charged in the capacitor C is driven from the driver 142 via the second transistor M2 and the data line Dm. Is supplied. The data driver 120 receiving the pixel current increases or decreases a current value to be supplied to the data line Dm so that a desired pixel current flows in the pixel 140.

Thereafter, when the first transistor M1 is turned on during the second period, a voltage corresponding to the current increased or decreased by the data driver 120 is charged in the capacitor C. FIG. In fact, in the present invention, the charging voltage of the capacitor C is controlled so that the desired pixel current can flow while the first transistor M1 is turned on and off at least once during the second period. In the present invention as described above, the sum of the first and second periods is set equal to or less than one horizontal period.

On the other hand, since the emission control signal is supplied to the nth emission control line En during the specific horizontal period, the third transistor M3 is turned off, and thus the pixel current is not supplied to the light emitting element OLED. Since the emission control signal is not supplied to the nth emission control line En after the specific horizontal period, the pixel current is supplied to the light emitting element OLED. Here, since the pixel current is set to a desired current value for a specific horizontal period, the light emitting device OLED may generate light having a desired luminance.

FIG. 5 is a diagram illustrating in detail the data integrated circuit shown in FIG. 2. 5 assumes that the data integrated circuit 129 has j channels for convenience of description.

Referring to FIG. 5, the data integrated circuit 129 may include a shift register unit 200 for sequentially generating sampling signals, and a sampling latch unit for sequentially storing data Data in response to the sapling signal. 210 and a holding latch for temporarily storing data of the sampling latch unit 210 and supplying the stored data to the current digital-to-analog converter (hereinafter, referred to as an “IDAC unit”) 230. The unit 220 controls an IDAC unit 230 for generating a gradation current Idata corresponding to the gradation value of the data, and a current value supplied from the pixel 140 in response to the pixel current Ipixel. And a selection block 250 for supplying the pixel current Ipixel from the pixel 140 to the current adjustment block 240 for a part of the horizontal period.

The shift register unit 200 receives a source shift clock SSC and a source start pulse SSP from the timing controller 150. The shift register unit 200 supplied with the source shift clock SSC and the source start pulse SSP generates j sampling signals sequentially while shifting the source start pulse SSP every one period of the source shift clock SSC. do. To this end, the shift register unit 200 includes j shift registers 2001 to 200j.

The sampling latch unit 210 sequentially stores data Data in response to sampling signals sequentially supplied from the shift register 200. Here, the sampling latch unit 210 includes j sampling latches 2101 to 210j to store j data. Each of the sampling latches 2101 to 210j has a size corresponding to the number of bits of the data. For example, when the data are k bits, each of the sampling latches 2101 to 210j is set to a size of k bits.

The holding latch unit 220 receives data from the sampling latch unit 210 and stores the data when the source output enable signal SOE is input. The holding latch 220 supplies the data Data stored therein to the IDAC unit 230 when the source output enable signal SOE is input. To this end, the holding latch unit 220 includes j holding latches 2201 to 220j set to k bits.

The IDAC unit 230 generates a gradation current Idata corresponding to the bit value of the data, and receives a current from the pixel 140 via the data line D by the generated gradation current Idata. . That is, the IDAC unit 230 sinks the current by the gradation current Idata corresponding to the bit value of the data. To this end, the IDAC unit 230 includes j current generation units 2301 to 230j.

The current adjustment block 240 is supplied with the gradation current Idata and the pixel current Ipixel. The current adjusting block 240 supplied with the gradation current idata and the pixel current Ipixel compares the current values of the gradation current idata and the pixel current Ipixel, and corresponds to the compared current difference to the pixel 140. Control current value supplied to. In practice, the current adjustment block 240 readjusts the current value so that the desired pixel current Ipixel can flow. To this end, the current adjustment block 240 is provided with j current adjustment units (2401 to 240j).

The selection block 250 connects the IDAC unit 230 and the data lines D1 to Dm during the first period of the horizontal period. When the IDAC unit 230 and the data lines D1 to Dm are electrically connected, current corresponding to the gradation current Idata is supplied from the pixels 140 to the IDAC unit 230. In addition, the selection block 250 connects the data lines D1 to Dm with the current adjustment block 240 for a part of the second period. At this time, the pixel current Ipixel from the pixel 140 is supplied to the current adjustment block 240. To this end, the selection block 250 includes j number of selection units 2501 to 250j.

Meanwhile, the data integrated circuit of the present invention may further include a level shifter unit 260 between the holding latch unit 220 and the IDAC unit 230 as shown in FIG. 6. The level shifter unit 260 increases the voltage level of data Data supplied from the holding latch unit 220 and supplies it to the IDAC unit 230. When data having a high voltage level is supplied to the data integrated circuit 129 from an external system, a manufacturing cost increases because circuit components corresponding to the voltage level need to be installed. Therefore, the data Data having a low voltage level is supplied from the outside of the data integrated circuit 129, and the data Data having the low voltage level is boosted by the level sheeter 260 to a high voltage level.

FIG. 7 is a detailed diagram illustrating the current adjuster and the selector illustrated in FIG. 5. In FIG. 7, the j th current adjuster 240j and the selector 250j are illustrated for convenience of description.

Referring to FIG. 7, the selector 250j of the present invention includes a fifth transistor M5 and a sixth transistor M6 and a data line Dj connected between the current generator 230j and the data line Dj. ) And a seventh transistor M7 connected between the current adjuster 240j and an eighth transistor M8 connected between the current adjuster 240j and the current generator 230j.

The fifth transistor M5 and the sixth transistor M6 are turned on at the same time to connect the data line Dj to the current generator 230j. To this end, the fifth transistor M5 and the sixth transistor M6 are controlled by the selection signal supplied from the control line CL.

The seventh transistor M7 and the eighth transistor M8 are alternately turned on with the fifth transistor M5. To this end, the seventh transistor M7 and the eighth transistor M8 are formed in a different conductivity type from the fifth transistor M5. When the seventh transistor M7 is turned on, the data line Dj is connected to the current adjuster 240j. When the eighth transistor M8 is turned on, the current adjuster 240j and the current generator 230j are connected.

As shown in FIG. 8, the selection signal is supplied such that the fifth transistor M5 and the sixth transistor M6 can be turned on during the first period of the horizontal period. The selection signal is supplied such that the fifth and sixth transistors M5 and M6 and the seventh and eighth transistors M8 are alternately turned on during the second period. During the second period, the selection signal is supplied such that the fifth transistor M5 and the sixth transistor M6 are turned on and off in the same manner as the first transistor M1.

The current generator 230j is configured as a current sink type. In other words, the current generator 230j receives the current from the outside (the pixel 140 or the current adjuster 240j) as much as the gradation current Idata corresponding to the data.

The current adjuster 240j includes a comparator 242 and a current controller 244. The comparator 242 receives the gradation current Idata supplied to the current generator 230j and the pixel current Ipixel supplied from the pixel 140. The comparison unit 242 supplied with the pixel current Ipixel compares the gradation current Idata and the pixel current Ipixel and supplies a control signal corresponding to the result to the voltage increase / decrease unit 244. For example, the comparator 242 generates the first control signal when the gradation current Idata is greater than the pixel current Ipixel, and the second control signal when the gradation current Idata is smaller than the pixel current Ipixel. Is generated and supplied to the current sensing unit 244.

The current controller 244 controls the current value of the first node N1, which is a common terminal of the fifth transistor M5 and the sixth transistor M6, in response to a control signal supplied from the comparator 242. Then, as the current value supplied to the pixel 140 increases or decreases, the charge voltage value of the capacitor C included in the driver 142 changes. Here, the current controller 244 controls the current value supplied to the pixel 140 so that the pixel current Ipixel and the gradation current Idata can be similar.

4, 7 and 8, the operation process will be described in detail. First, the first transistor M1 included in the pixel 140 by the first scan signal and the second scan signal during a first period of a specific horizontal period. ) And the second transistor M2 are turned on. Then, the fifth transistor M5 and the sixth transistor M6 are turned on during the first period of the horizontal period. When the first transistor M1, the second transistor M2, the fifth transistor M5, and the sixth transistor M6 are turned on, the current generator 230j and the pixel 140 are electrically connected to each other. Accordingly, a current corresponding to the gradation current Idata is supplied from the pixel 140 to the current generator 230j. At this time, the capacitor C included in the pixel 140 is charged with a predetermined voltage corresponding to the gradation current Idata. In fact, the first period is set so that the capacitor C included in the pixel 140 is charged with a voltage corresponding to the gradation current Idata.

When the second period begins after a predetermined voltage is charged in the capacitor C included in the pixel 140, the fifth transistor M5 and the sixth transistor M6 are turned off by the selection signal, and the seventh transistor is turned off. Transistor M7 and eighth transistor M8 are turned on. Then, when the second period starts, the first transistor M1 is turned off.

When the seventh transistor M7 is turned on, the pixel current Ipixel from the pixel 140 is supplied to the comparator 242 via the second transistor M2 and the seventh transistor M7. When the eighth transistor M8 is turned on, the gradation current Idata is supplied to the comparator 242. (Actually, a current corresponding to the gradation current Idata is supplied from the comparator 242 to the current generator 230j. At this time, the comparator 242 compares the gradation current Idata and the pixel current Ipixel, and supplies a control signal corresponding to the comparison result to the current controller 244.

The current controller 244 supplies a current to the first node N1 or receives a current from the first node N1 in response to the comparison result supplied from the comparator 242. That is, the comparison unit 242 increases or decreases the current value of the first node N1 in response to the comparison result. Here, the current controller 244 increases or decreases the current value so that the pixel current Ipixel and the gradation current Idata may be the same or similar.

Thereafter, the seventh and eighth transistors M7 and M8 are turned off by the selection signal, and the fifth and sixth transistors M5 and M6 are turned on. The first transistor M1 is turned on by the first scan signal. In this case, since the first transistor M1, the second transistor M2, the fifth transistor M5, and the sixth transistor M6 are turned on, a predetermined current from the pixel 140 is applied to the first node N1. Is supplied.

Here, the current supplied from the pixel 140 to the first node N1 is controlled by the current value that is increased or decreased by the current controller 244. For example, if the current controller 244 supplies the predetermined current Iid to the first node N1, the pixel current Ipixel supplied from the pixel 140 to the first node N1 is the grayscale current Idata. It is determined as a value obtained by subtracting the predetermined current Iid from. That is, the pixel current Ipixel, which is reduced from the first period, is supplied from the pixel 140, and thus the voltage value charged in the capacitor C is changed.

If the predetermined current Iid is supplied from the first node N1 to the current controller 244, the pixel current Ipixel supplied from the pixel 140 to the first node N1 is predetermined in the gradation current Idata. It is determined by adding the current Iid. That is, the pixel current Ipixel increased from the first period is supplied from the pixel 140, and accordingly, the voltage value charged in the capacitor C is changed.

In fact, in the present invention, the first transistor M1 is turned on and turned off at least once so that the gradation current Idata and the pixel current Ipixel become similar or the same during the second period. In addition, the fifth transistor M5 and the sixth transistor M6 are turned on and off in the same manner as the first transistor M1, and the seventh transistor M7 and the first transistor M1 are alternated with each other. The eighth transistor M8 is turned on. In the present invention, such a process is repeated a predetermined number of times, so that the desired pixel current Ipixel flows in the pixel 140.

9 is a diagram illustrating an example of the current controller illustrated in FIG. 7.

Referring to FIG. 9, the current control unit 244 includes a first transistor M11 and a second transistor M12 connected between a fixed voltage source VCC and a ground voltage source GND. The first transistor M11 and the second transistor M12 are formed of different conductivity types. Therefore, one of the first transistor M11 and the second transistor M12 is turned on in response to the control signal supplied from the comparator 242. Here, when the first transistor M11 is turned on, the predetermined current Iid of the first node N1 is supplied from the second node N2. When the second transistor M12 is turned on, the predetermined current Iid is supplied from the first node N1 to the second node N2.

And a third transistor M13 and a fourth transistor M14 connected between the current controller current control unit 1 transistor M11 and the second transistor M12. The third transistor M13 and the fourth transistor M14 are controlled by the selection signal supplied to the control line CL as shown in FIG. 8. That is, the third transistor M13 and the fourth transistor M14 are turned on and turned off in the same manner as the fifth transistor M15 and the sixth transistor M16.

FIG. 10 is a diagram illustrating an example of the comparison unit illustrated in FIG. 7. The comparison unit shown in FIG. 10 was known from the Institute of Electrical and Electronics Engineers (IEEE) in 1992. In practice, various known comparison units capable of comparing current values can be used in the present invention.

Referring to FIG. 10, the third node N3 is supplied with a current corresponding to the difference between the pixel current Ipixel and the gradation current Idata. The current supplied to the third node N3 is supplied to the gate terminals of the third transistor M23 and the fourth transistor M24 composed of inverters. Then, any one of the third transistor M23 and the fourth transistor M24 is turned on and the high voltage VCC or the low voltage GND is applied to the output. Here, the voltage applied to the output unit is supplied to the gate terminals of the first transistor M21 and the second transistor M21 so that the voltage of the output unit is stably maintained.

11 is a diagram illustrating a pixel according to a second exemplary embodiment of the present invention.

Referring to FIG. 11, a pixel according to a second embodiment of the present invention includes a light emitting device OLED, a first transistor M1, a second transistor M2, a third transistor M3, and a driver 142. do.

The first transistor M1 is connected between the data line Dm and the driver 142 to electrically connect the data line Dm and the driver 142. As shown in FIG. 12, the first transistor M1 is controlled by the first scan signal supplied to the n-th first scan line S1n.

The second transistor M2 is connected between the driving unit 142 and the common terminal of the light emitting element OLED and the data line Dm to electrically connect the data line Dm and the driving unit 142. As shown in FIG. 12, the second transistor is controlled by the second scan signal supplied to the n-th second scan line S2n.

The third transistor M3 is connected between the driver 142 and the light emitting device OLED. The third transistor M3 is turned off when the second transistor M2 is turned on, and is turned on when the second transistor M2 is turned off. To this end, the third transistor M3 is formed of a different conductivity type from the second transistor M2 and is controlled by a second scan signal supplied to the nth second scan line S2n.

The driver 142 supplies a pixel current corresponding to the data signal to the second transistor M2 and the third transistor M3. To this end, the driver 142 includes a capacitor C for charging a voltage corresponding to the data signal and a fourth transistor M4 for supplying a pixel current corresponding to the voltage charged to the capacitor C. .

11 and 12, the operation process is described in detail. First, the first scan signal is supplied to the nth first scan line S1n during a specific horizontal period of one frame, and the nth second scan line S2n is applied to the nth second scan line S2n. Two scan signals are supplied.

When the second scan signal is supplied to the nth second scan line S2n, the second transistor M2 is turned on for a specific horizontal period. When the second scan signal is supplied, the third transistor M3 is turned off for a specific horizontal period.

When the first scan signal is supplied to the nth first scan line S1n, the first transistor M1 is turned on during the first period of the specific horizontal period. When the first transistor M1 is turned on, a predetermined current corresponding to the gradation current is supplied from the pixel to the data driver 120. At this time, the capacitor C included in the driver 142 is charged with a voltage corresponding to a predetermined current. When the first transistor M1 is turned off during the second period, the pixel current corresponding to the voltage charged in the capacitor C is supplied to the data driver 120. The data driver 120 receiving the pixel current increases or decreases a current value to be supplied to the data line Dm so that a desired pixel current flows in the pixel 140. In practice, during the second period, the first transistor M1 controls the voltage value charged in the capacitor C so that a desired pixel current can flow while repeating turn-on and turn-off at least once.

On the other hand, the pixel current is not supplied to the light emitting device OLED because the third transistor M3 is turned off during the specific horizontal period. When the third transistor M3 is turned on in response to the second scan signal after the specific horizontal period, the pixel current is supplied to the light emitting device OLED. Here, since the pixel current is changed to a desired current value during a specific horizontal period, the light emitting device OLED may generate light having a desired brightness.

13 is a diagram illustrating a pixel according to a third exemplary embodiment of the present invention.

Referring to FIG. 13, a pixel according to a third exemplary embodiment of the present invention includes a light emitting device OLED, a first transistor M1, a second transistor M2, a third transistor M3, a connection transistor MT, and the like. The driving unit 142 is provided.

The first transistor M1 is connected between the data line Dj and the driver 142 to electrically connect the data line Dj and the driver 142. The first transistor M1 is controlled by the first scan signal supplied to the n-th first scan line S1n.

The second transistor M2 is connected between the driving unit 142 and the common terminal of the light emitting element OLED and the feedback line Fj to electrically connect the feedback line Fj and the driving unit 142. Here, the feedback line Fj is connected to the current adjuster 240j via the seventh transistor M7. Therefore, the seventh transistor M7 and the data line Dm are electrically isolated. The second transistor is controlled by the second scan signal supplied to the n-th second scan line S2n.

The connection transistor MT is connected between the first transistor M1 and the second transistor M2 to electrically connect the data line Dm and the feedback line Fm. The connection transistor MT is controlled by the first scan signal supplied to the n-th first scan line S1n. That is, the connection transistor MT is turned on and turned off in the same manner as the first transistor M1.

The third transistor M3 is connected between the driver 142 and the light emitting device OLED. The third transistor M3 is turned off when the second transistor M2 is turned on, and is turned on when the second transistor M2 is turned off. To this end, the third transistor M3 is controlled by the emission control signal supplied from the emission control line En as shown in FIG. 4.

The driver 142 supplies a pixel current corresponding to the data signal to the second transistor M2 and the third transistor M3. To this end, the driver 142 includes a capacitor C for charging a voltage corresponding to the data signal and a fourth transistor M4 for supplying a pixel current corresponding to the voltage charged to the capacitor C. .

4 and 13, the operation process will be described in detail. First, the first scan signal is supplied to the n th first scan line S1n during a specific horizontal period of one frame and the n th second scan line S2n is simultaneously applied. Two scan signals are supplied. The light emission control signal is supplied to the light emission control line En during the specific horizontal period.

When the second scan signal is supplied to the nth second scan line S2n, the second transistor M2 is turned on for a specific horizontal period. When the emission control signal is supplied to the emission control line En, the third transistor M3 is turned off for a specific horizontal period.

When the first scan signal is supplied to the nth first scan line S1n, the first transistor M1 and the connection transistor M5 are turned on during the first period of the specific horizontal period. When the first transistor M1 and the connection transistor M5 are turned on, a predetermined current corresponding to the gradation current is supplied from the pixel to the data driver 120. At this time, the capacitor C included in the driver 142 is charged with a voltage corresponding to a predetermined current.

Then, the first transistor M1 is turned off for a part of the second period. At this time, the pixel current from the driver 142 is supplied to the data driver 120 via the feedback line Fm. The data driver 120 receiving the pixel current increases or decreases a current value to be supplied to the data line Dj so that a desired pixel current flows in the pixel 140. In fact, during the second period, the first transistor M1 controls the voltage value charged in the capacitor C so that a desired pixel current can flow while repeating turn-on and turn-off at least once.

On the other hand, the pixel current is not supplied to the light emitting device OLED because the third transistor M3 is turned off during the specific horizontal period. When the third transistor M3 is turned on after the specific horizontal period, the pixel current is supplied to the light emitting device OLED. Here, since the pixel current is changed to a desired current value during a specific horizontal period, the light emitting device OLED may generate light having a desired brightness.

Meanwhile, the pixels described in the present invention may be changed to NMOS transistors as shown in FIG. 14. In fact, the pixel shown in FIG. 14 is configured by changing the PMOS transistors shown in FIG. 3 to NMOS transistors. When the pixels are changed to the NMOS transistor as shown in FIG. 14, the polarities of the signals (the first scan signal, the second scan signal, the light emission control signal, etc.) are reversed as is well known to those skilled in the art. same.

The above detailed description and drawings are merely exemplary of the present invention, which are used only for the purpose of illustrating the present invention and are not intended to limit the scope of the present invention as defined in the claims or the claims. Accordingly, those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical protection scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

As described above, according to the pixel and the light emitting display device using the same according to the embodiment of the present invention, the gradation current corresponding to the data and the pixel current flowing in the pixel are compared, and the pixel current is similar to the gradation current in response to the comparison result. The current value supplied to the pixel is controlled to be changed to the current value. That is, in the present invention, it is possible to control the desired pixel current to flow through the pixel, thereby displaying an image having a desired brightness.

Claims (9)

A light emitting element, A first transistor for repeating at least one turn-on and turn-off during a specific horizontal period in response to a first scan signal supplied from the first scan line; A second transistor for maintaining a turn-on state for the specific horizontal period in response to a second scan signal supplied from a second scan line; And a driver for supplying the pixel current corresponding to the data signal supplied from the data line via the first transistor to the light emitting element. The method of claim 1, And the first transistor is connected between the data line and the driver and is turned on for a first period of the specific horizontal period, and is turned on and off at least once for a second period except the first period. The method of claim 2, And the second transistor is connected between the common terminal of the driving unit and the light emitting element and the data line. The method of claim 1, And a third transistor connected between the driving unit and the light emitting element and turned off during the specific horizontal period in response to a light emission control signal supplied from a light emission control line, and turned on for the other period. The method of claim 1, And a third transistor connected between the driving unit and the light emitting element and turned off during the specific horizontal period in response to the second scan signal, and turned on during the other period. The method of claim 5, The third transistor is formed of a different conductivity type than the second transistor. The method of claim 2, And the second transistor is connected to a common terminal of the driving unit and the light emitting device and a feedback line formed in parallel with the data line. The method of claim 7, wherein And a third transistor connected between the first transistor and the second transistor, the third transistor being turned on and off in the same manner as the first transistor in response to the first scan signal. A plurality of first scan lines and second scan lines; A plurality of data lines formed in a direction crossing the first scan line and the second scan line; An image display unit including a plurality of pixels connected to the first scan line, the second scan line, and the data line; A scan driver which sequentially supplies a first scan signal to the first scan line and sequentially supplies a second scan signal to the second scan line; The first current corresponding to the gradation current is connected to the data lines, and receives the first current from the pixels, and compares the pixel current flowing in the pixels with the gradation current corresponding to the first current, thereby comparing the current value of the first current. A data driver for increasing or decreasing the number; The pixel is a light emitting display device according to any one of claims 1 to 8.

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