KR102593328B1 - Organic light emitting display apparatus - Google Patents

Abstract

An object of the present invention is to provide an organic light emitting display device capable of charging an initialization voltage in a storage capacitor for two horizontal periods before a data voltage is charged in the storage capacitor.

Description

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

The present invention relates to an organic light emitting display device.

When an organic light emitting display panel is used for a long time, the driving transistor that supplies current to the organic light emitting diode may deteriorate, and when the driving transistor deteriorates, image quality deteriorates.

In order to compensate for the deterioration of the driving transistor as described above, the pixel driving circuit for controlling the organic light emitting diode is provided with a plurality of transistors in addition to the driving transistor.

In a pixel driving circuit including a plurality of transistors, an operation for sensing the threshold voltage of the driving transistor and an operation for charging a storage capacitor with a data voltage may be performed simultaneously.

In this case, before the data voltage is charged, the storage capacitor is charged with an initialization voltage.

In a conventional organic light emitting display panel including a pixel driving circuit equipped with seven transistors to compensate for the deterioration of the driving transistor, the initialization occurs in one horizontal period (the period in which the data voltage is supplied to the data line, 1H). Voltage is charged to the storage capacitor.

However, in a conventional organic light emitting display panel that has high resolution and is driven at a high frequency, the initialization voltage does not sufficiently charge the storage capacitor during the 1H.

Accordingly, spot defects occur in conventional organic light emitting display panels.

The purpose of the present invention proposed to solve the above-described problem is to provide an organic light emitting display device that can charge the storage capacitor with an initialization voltage for two horizontal periods before the data voltage is charged in the storage capacitor.

An organic light emitting display device according to the present invention for achieving the above-described technical problem includes an organic light emitting display panel having pixels including an organic light emitting diode and a pixel driver circuit for driving the organic light emitting diode, and the organic light emitting display panel. It includes a driver that supplies data voltages to data lines provided in the organic light emitting display panel and supplies scan signals to scan lines provided in the organic light emitting display panel. The pixel driving circuit includes a driving transistor that controls the current supplied to the organic light emitting diode and a storage capacitor that charges the data voltage supplied from the data driver and the threshold voltage of the driving transistor. During the second horizontal period, which is twice as long as the first horizontal period during which the data voltage is supplied to the data line, an initialization voltage that initializes the first node connected to the gate of the driving transistor is charged in the storage capacitor.

According to the present invention, after the initialization voltage is charged in the storage capacitor for two horizontal periods longer than the conventional one horizontal period, the threshold voltage and data voltage of the driving transistor can be charged in the storage capacitor.

Accordingly, the initialization voltage can be normally charged in the storage capacitor, and accordingly, the data voltage can also be normally charged in the storage capacitor.

As the storage capacitor is charged with a normal data voltage, light with normal brightness according to the data voltage may be output from the organic light emitting diode.

Therefore, according to the present invention, in an organic light emitting display panel driven at a high frequency, spot defects due to abnormal charging of the initialization voltage may not occur.

1 is an exemplary diagram showing the configuration of an organic light emitting display device according to the present invention.
Figure 2 is an exemplary diagram showing the configuration of a pixel applied to an organic light emitting display device according to the present invention.
Figure 3 is an example diagram showing waveforms of signals applied to an organic light emitting display device according to the present invention.
4 to 8 are exemplary views showing how the organic light emitting display device according to the present invention is driven.
9 is graphs illustrating the effect of the organic light emitting display device according to the present invention.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms. These embodiments only serve to ensure that the disclosure of the present invention is complete, and those skilled in the art It is provided to fully inform the person of the scope of the invention, and the present invention is only defined by the scope of the claims.

In this specification, it should be noted that when adding reference numbers to components in each drawing, the same components are given the same number as much as possible even if they are shown in different drawings.

The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the present invention are illustrative, and the present invention is not limited to the matters shown. Like reference numerals refer to like elements throughout the specification. Additionally, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. When 'includes', 'has', 'consists of', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the plural is included unless specifically stated otherwise.

When interpreting a component, it is interpreted to include the margin of error even if there is no separate explicit description.

In the case of a description of a positional relationship, for example, if the positional relationship of two parts is described as 'on top', 'on the top', 'on the bottom', 'next to', etc., 'immediately' Alternatively, there may be one or more other parts placed between the two parts, unless 'directly' is used.

In the case of a description of a temporal relationship, for example, if a temporal relationship is described as 'after', 'successfully after', 'after', 'before', etc., 'immediately' or 'directly' Unless used, non-consecutive cases may also be included.

The term ‘at least one’ should be understood to include all possible combinations from one or more related items. For example, 'at least one of the first item, the second item and the third item' means each of the first item, the second item or the third item, as well as two of the first item, the second item and the third item. It means a combination of all items that can be presented from more than one.

Although first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are merely used to distinguish one component from another. Accordingly, the first component mentioned below may also be the second component within the technical spirit of the present invention.

Each feature of the various embodiments of the present invention can be partially or fully combined or combined with each other, various technical interconnections and operations are possible, and each embodiment can be implemented independently of each other or together in a related relationship. It may be possible.

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

Figure 1 is an exemplary diagram showing the configuration of an organic light emitting display device according to the present invention, and Figure 2 is an exemplary diagram showing the configuration of a pixel applied to the organic light emitting display device according to the present invention. Although FIG. 2 shows transistors configured as P-type, the organic light emitting display panel according to the present invention is not limited to P-type transistors.

As shown in FIGS. 1 and 2, the organic light emitting display device according to the present invention includes a pixel (110) including an organic light emitting diode (OLED) and a pixel driver circuit (PDC) that drives the organic light emitting diode (OLED). ) is provided to the organic light emitting display panel 100 and data voltages (Vdata) are supplied to the data lines (DL1 to DLd) provided in the organic light emitting display panel 100, and provided in the organic light emitting display panel. It includes a driver that supplies scan signals to the scan lines.

Here, the driving unit is a data driver 300 that supplies data voltages (Vdata) to the pixel driving circuits (PDCs) provided in the pixels 110 through the data lines (DL1 to DLd), A first scan signal (SCAN(n)) is supplied to the first scan lines (GL1 to Glg), and a second scan signal (SCAN(n-1)) is supplied to the second scan lines (SCL), A gate driver 200 that supplies a third scan signal (SCAN(n+1)) to the third scan lines (SL) and an emission signal (EM(n)) to the emission line (EL), and It includes a control unit 400 that controls driving of the data driver 300 and the gate driver 200. Additionally, the organic light emitting display device includes a power supply unit that supplies power required for the components.

Below, the above components are described sequentially.

First, as shown in FIGS. 1 and 2, the organic light emitting display panel 100 includes the pixels 110, the data lines DL1 to Dld, and the scan lines GL, SCL, and SL. , EL), initialization lines (IL) to which the initialization voltage is supplied, the emission lines (EL), first driving voltage lines (PLA), and second driving voltage lines (PLB) are provided.

The first scan lines GL1 to GLg may be formed side by side at regular intervals along the first direction of the organic light emitting display panel 100, for example, the horizontal direction. First scan signals SCAN(n) are supplied from the gate driver 200 to the pixel driving circuits PDC through the first scan lines GL1 to GLg.

The second scan lines SCL may be formed parallel to the first scan lines GL along the first direction. Second scan signals (SCAN(n-1)) are supplied from the gate driver 200 to the pixel driving circuits (PDC) through the second scan lines (SCL).

The third scan lines SL may be formed parallel to the first scan lines GL along the first direction. Third scan signals (SCAN(n+1)) are supplied from the gate driver 200 to the pixel driving circuits (PDC) through the third scan lines (SL).

The data lines (DL1 to DLd) include the first scan line (GL), the second scan line (SCL), the third scan line (SL), the initialization line (IL), and the emission line ( EL) may be formed side by side at regular intervals along the second direction, for example, the vertical direction, of the organic light emitting display panel 100. Data voltages (Vdata) are supplied to the data lines (DL).

The first driving voltage lines (PLA) may be formed parallel to the data lines (DL) along the second direction and are spaced apart from the data lines (DL) at regular intervals. The first driving voltage lines (PLA) are connected to the power supply unit and supply the first driving voltage (VDD) supplied from the power supply unit to the pixels 110.

The second driving voltage lines (PLB) supply the second driving voltages (VSS) supplied from the power supply to the pixels 110.

The emission lines EL may extend in the first direction. Emission signals (EM) that control the emission timing of the organic light emitting diode (OLED) are supplied from the gate driver 200 to the pixel driving circuit (PDC) through the emission lines (EL). In FIG. 2, the emission line EL is divided into two strands, but the emission line EL may be formed as one line.

The initialization lines IL may extend in the first direction or in the second direction. The initialization voltages (Vinit) are supplied from the power supply unit to the pixel driving circuits (PDC) through the initialization lines (IL).

Each of the pixels 110 is provided with the organic light emitting diode (OLED) and the pixel driving circuit (PDC).

The pixel driving circuit (PDC) includes a driving transistor (Tdr) and a storage capacitor (Cst) that control the amount of current supplied to the organic light emitting diode (OLED). The pixel driving circuit (PDC) includes first to seventh transistors (T1 to T7), as shown in FIG. 2, in addition to the driving transistor (Tdr) and the storage capacitor (Cst).

That is, the pixel driving circuit (PDC) includes the driving transistor (Tdr), which controls the current (Ioled) supplied to the organic light-emitting diode (OLED), and the data voltage (Vdata) supplied from the data driver 300. It includes a storage capacitor (Cst) that charges the threshold voltage of the driving transistor (Tdr).

In this case, before the data voltage (Vdata) is charged in the storage capacitor (Cst), the data voltage (Vdata) is supplied to the data line (DL) for 2 horizontal periods (2 times the 1 horizontal period (1H)). During 2H), the initialization voltage Vinit, which initializes the first node N1 connected to the gate of the driving transistor Tdr, may be charged in the storage capacitor Cst.

To this end, the pixel driving circuit (PDC) has the driving transistor (Tdr), one end of which is connected to the first node (N1), and the other end of which is connected to the organic light emitting diode (OLED) to apply the first driving voltage (VDD). The storage capacitor (Cst) is connected to the first driving voltage line (PLA), and is connected to the driving transistor (Tdr) and the storage capacitor (Cst), and the voltage charged in the storage capacitor (Cst) It includes 7 transistors (T1 to T7) to change .

In this case, in the first period, for one horizontal period (1H), the initialization voltage (Vinti) is supplied to the first node (N1), and in the second period, for one horizontal period (1H), the first node (N1) The initialization voltage Vinit is supplied to the node N1, and in the third period, during one horizontal period 1H, the threshold voltage and the data voltage Vdata of the driving transistor Tdr are supplied to the first node N1. ) is supplied, and in the fourth period, for one horizontal period (1H), the first node (N1) is maintained at the threshold voltage of the driving transistor (Tdr) and the data voltage (Vdata), and in the fifth period , During one horizontal period (1H), the driving transistor (Tdr) passes a current (Ioled) corresponding to the data voltage (Vdata) to the organic light emitting diode (OLED). Here, in the fourth period, the first node (N1) is maintained at the threshold voltage and the data voltage (Vdata). This means that the voltage of the first node (N1) is maintained at the threshold voltage and the data voltage (Vdata). ) means that it is maintained at the combined voltage.

That is, because the first node (N1) is the one end of the storage capacitor (Cst), the voltages supplied to the first node (N1) can charge the storage capacitor (Cst).

In the fifth period, the current (Ioled) supplied to the organic light emitting diode (OLED) through the driving transistor (Tdr) is not affected by the threshold voltage of the driving transistor (Tdr).

That is, in the present invention, the current (Ioled) supplied to the organic light emitting diode (OLED) through the driving transistor (Tdr) is not affected by the threshold voltage of the driving transistor (Tdr).

This compensation method is called an internal compensation method.

Components constituting the pixel driving circuit (PDC) may be divided by function.

That is, the pixel driving circuit (PDC) includes the driving transistor (Tdr) whose first and second terminals are connected to the first driving voltage line (PLA), and whose first end is connected to the gate of the driving transistor. The storage capacitor (Cst) connected to the node (N1) and the other end connected to the first driving voltage line (PLA) that supplies the first driving voltage (VDD) to the organic light emitting diode (OLED), the driver , In particular, at least one emission unit 111 that is turned on or off according to the emission signal EM(n) transmitted from the gate driver 200 to control the emission timing of the organic light emitting diode (OLED). ), a first scan signal (SCAN(n)) and a third scan signal (SCAN(n)) connected between the driving transistor (Tdr) and the data line (DL) and transmitted from the driving unit, especially the gate driver 200 A switching unit 112 that is turned on according to SCAN (n+1)) and charges the data voltage (Vdata) and the threshold voltage in the storage capacitor (Cst), and the driver, especially the gate driver 200 It includes an initialization unit 113 that is turned on or off according to a second scan signal (SCAN(n-1)) transmitted from and charges the initialization voltage (Vinit) in the storage capacitor (Cst).

In this case, in the first period, during one horizontal period (1H), the first node (N1) between the storage capacitor (Cst) and the gate of the driving transistor (Tdr) through the initialization charging unit 113 is An initialization voltage (Vinit) is supplied, and in the second period, the initialization voltage (Vinit) is supplied to the first node (N1) through the initialization charging unit 113 for one horizontal period (1H), In the third period, during one horizontal period (1H), the threshold voltage and the data voltage ( Vdata) is supplied, and in the fourth period, for one horizontal period (1H), the voltage of the first node (N1) is maintained at the threshold voltage of the driving transistor (Tdr) and the data voltage (Vdata), In the fifth period, during one horizontal period (1H), a current (Ioled) corresponding to the data voltage (Vdata) is supplied to the organic light emitting diode (OLED) through the driving transistor (Tdr) and the emission unit 111. is supplied as

The components of the pixel driving circuit (PDC) will be described in more detail as follows.

That is, the pixel driving circuit (PDC) includes the driving transistor (Tdr) whose first and second terminals are connected to the first driving voltage line (PLA), and one end of which is the gate of the driving transistor (Tdr), i.e. , the storage capacitor (Cst) is connected to the first node (N1) and the other end is connected to the first driving voltage line (PLA), the gate is connected to the driver, in particular, the gate driver 200, A first transistor (T1), the first terminal of which is connected to the other terminal of the storage capacitor (Cst), the second terminal of which is connected to the first terminal of the driving transistor (Tdr), and the gate of which is connected to the driver, in particular, the A second transistor (T2) connected to the gate driver 200, the first terminal of which is connected to the data line (DL), and the second terminal of which is connected to the first terminal of the driving transistor (Tdr), the gate is The driver, in particular, is connected to the gate driver 200, and has a first terminal connected to the second terminal of the driving transistor, and the second terminal is the gate of the driving transistor (Tdr), that is, the first node. A third transistor (T3) connected to (N1), the gate of which is connected to the driver, especially the gate driver 200, the initialization voltage (Vinit) is supplied to the first terminal, and the second terminal is connected to the The gate of the driving transistor Tdr, that is, the fourth transistor T4 connected to the first node N1, the gate is connected to the driving unit, in particular, the gate driver 200, and the first terminal is connected to the first node N1. 3 A fifth transistor (T5) connected to the first terminal of the transistor (T3), the second terminal of which is connected to the second terminal of the driving transistor (Tdr), the gate of which is connected to the driver, especially the gate driver ( 200), a first terminal is connected to the second terminal of the driving transistor (Tdr), a sixth transistor (T6) is connected to the organic light emitting diode (OLED), and a gate is connected to the second terminal of the driving transistor (Tdr). A driver, in particular, is connected to the gate driver 200, has a first terminal connected to the first terminal of the fourth transistor T4, and has a second terminal connected to the second terminal of the sixth transistor T6. It includes a seventh transistor (T7) connected to.

In this case, the emission unit 111 includes the first transistor (T1) and the sixth transistor (T6), and the switching unit 112 includes the second transistor (T2) and the third transistor. (T3), and the fifth transistor (T5), and the initialization unit 113 includes the fourth transistor (T4) and the seventh transistor (T7).

The first transistor (T1) and the sixth transistor (T6) are turned on or off by the emission signal (EM) transmitted from the driver, especially the gate driver 200, and the second transistor (T2) ) and the fifth transistor (T5) is turned on or off by the first scan signal (SCAN(n)) transmitted from the driver, in particular, the gate driver 200, and the fourth transistor (T4) and The seventh transistor (T7) is turned on or off by the second scan signal (SCAN(n-1)) transmitted from the driver, especially the gate driver 200, and the third transistor (T3) is It is turned on or off by the third scan signal (SCAN(n+1)) transmitted from the driver, especially the gate driver 200.

In the first period, during one horizontal period (1H), at the first node (N1) between the one end of the storage capacitor (Cst) and the gate of the driving transistor (Tdr) through the fourth transistor (T4) The initialization voltage (Vinit) is supplied, and in the second period, the initialization voltage (Vinit) is supplied to the first node (N1) through the fourth transistor (T4) for one horizontal period (1H). , In the third period, during one horizontal period (1H), through the second transistor (T2), the driving transistor (Tdr), the fifth transistor (T5), and the third transistor (T3), the first The threshold voltage and data voltage (Vdata) of the driving transistor (Tdr) are supplied to 1 node (N1), and in the fourth period, during 1 horizontal period (1H), the voltage of the first node (N1) is It is maintained at the threshold voltage of the driving transistor (Tdr) and the data voltage (Vdata), and in the fifth period, during one horizontal period (1H), the current (Ioled) corresponding to the data voltage (Vdata) is maintained at the first It is supplied to the organic light emitting diode (OLED) through the transistor T1, the driving transistor Tdr, and the sixth transistor T6.

The voltages supplied to the first node N1 are charged to the storage capacitor Cst.

That is, in the present invention, the initialization voltage is applied to the storage capacitor Cst during one horizontal period (1H) of the first period and one horizontal period (1H) of the second period, that is, for a total of two horizontal periods (2H). (Vinit) is charged. Accordingly, the storage capacitor Cst can be sufficiently charged with the initialization voltage Vinit.

Accordingly, the data voltage (Vdata) and the threshold voltage supplied to the first node (N1) in the third period can be normally charged in the storage capacitor (Cst), and thus, the first node (N1) ) can be maintained at a normal voltage corresponding to the sum of the data voltage (Vdata) and the threshold voltage.

For example, if the initialization voltage (Vinit) is not normally charged in the storage capacitor (Cst) in the first period and the second period, the first node (N1) will be maintained at the initialization voltage (Vinit). I can't.

In the above-described state, when the data voltage (Vdata) and the threshold voltage are supplied to the first node (N1) in the third period, the first node (N1) supplies the data voltage for one horizontal period. (Vdata) and the threshold voltage cannot be accurately reached.

If the voltage of the first node (N1) does not accurately correspond to the data voltage (Vdata) and the threshold voltage, the current (Ioled) passing through the driving transistor (Tdr) does not accurately correspond to the data voltage (Vdata). You won't be able to do it. Accordingly, the organic light emitting diode (OLED) may output light with a brightness that does not correspond to the actual data voltage (Vdata), and accordingly, spots may occur in the organic light emitting display panel.

Here, the one horizontal period (1H) refers to a period during which the data voltage (Vdata) is supplied from the data driver 300 to the data line (DL).

To explain further, if the one horizontal period (1H) is a period sufficient for the initialization voltage (Vinit) to be fully charged in the storage capacitor (Cst), any of the first period and the second period One may be omitted.

However, since organic light emitting display devices using high resolution organic light emitting display panels are driven using high frequencies, the one horizontal period (1H) is shortened.

Accordingly, in an organic light emitting display device driven at high speed, the initialization voltage Vinit cannot sufficiently charge the storage capacitor Cst during the one horizontal period (1H), and thus, the stain defect as described above occurs. It can be.

To prevent this problem, in the present invention, the initialization voltage Vinit is supplied to the first node N1 during the first period and the second period, that is, a total of two horizontal periods (2H). , For this purpose, the pixel driving circuit (PDC) has the structure described above.

Specific details of the operations performed in the first to fifth periods will be described in detail below with reference to FIGS. 3 to 9.

Second, the gate driver 200 sequentially supplies gate pulses to the first scan lines GL1 to GLg using the gate control signals GCS transmitted from the control unit 400.

Here, the gate pulse refers to a signal that can turn on the second transistor (T2) and the fifth transistor (T5) connected to the first scan lines (GL1 to GLg). A signal that can turn off the second transistor (T2) and the fifth transistor (T5) is called a gate-off signal. The gate pulse and the gate off signal are collectively referred to as the first scan signal (SCAN(n)).

In addition to the first scan signal SCAN(n), the gate driver 200 supplies the second scan signals SCAN(n-1) to the second scan lines SCL. The second scan signal (SCAN(n-1)) also includes a gate pulse capable of turning on the fourth transistor (T4) and the seventh transistor (T7), and the fourth transistor (T4) and the seventh transistor (T7) It includes a gate off signal that can turn off (T7).

In addition to the first scan signal (SCAN(n)) and the second scan signal (SCAN(n-1)), the gate driver 200 performs the third scan line (SL) using the third scan line (SL). It supplies signals (SCAN(n+1)). The third scan signal SCAN(n+1) also includes a gate pulse capable of turning on the third transistor T3 and a gate off signal capable of turning off the third transistor T3.

Here, n refers to the order of stages that output the first scan signal (SCAN(n)) to the first scan line (GL).

That is, the gate driver 200 includes first to g-th stages to sequentially supply the gate pulse of the first scan signal (SCAN(n)) to the first scan lines (GL1 to GLg). This can be done, and each stage is connected to the first scan line GL.

Therefore, n refers to the signal output from the nth stage, n-1 refers to the signal output from the n-1th stage, and n+1 refers to the signal output from the n+1th stage.

Additionally, the gate driver 200 supplies the emission signals (EM) to the emission lines (EL). The emission signal (EM) also has a gate pulse that can turn on the first transistor (T1) and the sixth transistor (T6) and a gate pulse that can turn off the first transistor (T1) and the sixth transistor (T6). Includes a gate-off signal that can be turned on.

The gate driver 200 is formed independently from the organic light emitting display panel 100 and is connected to the organic light emitting display panel through a tape carrier package (TCP), chip-on-film (COF), or flexible printed circuit board (FPCB). It can be connected to (100). However, the gate driver 200 is directly installed on the outside of the organic light emitting display panel 100 through the manufacturing process of the pixel driver circuits (PDCs) using the gate in panel (GIP) method. may be formed.

Third, the power supply unit supplies power to the gate driver 200, the data driver, and the control unit 400. In particular, the power supply unit may supply the initialization voltages Vinit to the initialization lines IL.

Fourth, the control unit 400 uses a timing synchronization signal input from an external system to control the gate control signal (GCS) for controlling the driving of the gate driver 200 and the driving of the data driver 300. Generates a data control signal (DCS) for each. Additionally, the control unit 400 converts input image data input from the external system into image data and transmits the image data to the data driver 300.

In order to perform the above-described function, the control unit 400 rearranges the input image data transmitted from the external system using a timing synchronization signal transmitted from the external system and sends the rearranged image data to the data driver. (300), a control signal generator for generating the gate control signal (GCS) and the data control signal (DCS) using the timing synchronization signal, and the timing transmitted from the external system. An input unit for distributing a synchronization signal and the input image data to the data arrangement unit and the control signal generation unit, and the image data generated in the data arrangement unit and the control signals (DCS, It may include an output unit for outputting GCS) to the data driver 300 or the gate driver 200.

Figure 3 is an example diagram showing waveforms of signals applied to an organic light emitting display device according to the present invention, and Figures 4 to 8 are examples showing how the organic light emitting display device according to the present invention is driven.

First, in the first period (A), as shown in FIGS. 3 and 4, the high-level first scan signal (SCAN(n)) is transmitted to the second transistor (T2) and the fifth transistor (T5). is supplied, a low-level second scan signal (SCAN(n-1)) is supplied to the fourth transistor (T4) and the seventh transistor (T7), and a high-level third scan signal (SCAN(n+) 1)) is supplied to the third transistor (T3), and a high level emission signal (EM(n)) is supplied to the first transistor (T1) and the sixth transistor (T6).

Accordingly, as shown in FIG. 4, the first to third transistors (T1 to T3), the fifth transistor (T5), and the sixth transistor (T6) are all turned off, and the fourth transistor ( T4) and the seventh transistor (T7) are turned on.

In this case, the initialization voltage Vinit is supplied to the gate of the driving transistor Tdr, that is, the first node N1, through the fourth transistor T4. The first node N1 is one end of the storage capacitor Cst, and is a node to which the storage capacitor Cst and the driving transistor Tdr are connected.

Accordingly, the voltage (VN1) of the first node (hereinafter simply referred to as the first node voltage) is initialized to the initialization voltage (Vinit).

That is, in the first period (A), for one horizontal period (1H), the first voltage between the one end of the storage capacitor (Cst) and the gate of the driving transistor (Tdr) through the fourth transistor (T4) The initialization voltage (Vinit) is supplied to the 1 node (N1), and the initialization voltage (Vinit) is charged to the storage capacitor (Cst). Therefore, the first node (N1) is supplied with the initialization voltage (Vinit). It is initialized. That is, the voltage of the first node (N1) becomes the initialization voltage (Vinit).

Next, in the second period (B), as shown in FIGS. 3 and 5, the low-level first scan signal (SCAN(n)) is transmitted to the second transistor (T2) and the fifth transistor (T5). is supplied, a low-level second scan signal (SCAN(n-1)) is supplied to the fourth transistor (T4) and the seventh transistor (T7), and a high-level third scan signal (SCAN(n+) 1)) is supplied to the third transistor (T3), and a high level emission signal (EM(n)) is supplied to the first transistor (T1) and the sixth transistor (T6).

Accordingly, as shown in FIG. 5, the second transistor (T2), the driving transistor (Tdr), the fifth transistor (T5), the seventh transistor (T7), and the fourth transistor (T4) It is turned on, and the first transistor (T1), the sixth transistor (T6), and the third transistor (T3) are all turned off. In this case, the driving transistor (Tdr) may be turned on by the first node voltage (VN1).

In this case, the initialization voltage Vinit is supplied to the gate of the driving transistor Tdr, that is, the first node N1, through the fourth transistor T4.

Accordingly, the first node N1 is initialized to the initialization voltage Vinit, as in the first period A.

That is, in the second period (B), for one horizontal period (1H), the first voltage between the one end of the storage capacitor (Cst) and the gate of the driving transistor (Tdr) through the fourth transistor (T4) 1 The initialization voltage is supplied to node N1. Accordingly, the storage capacitor Cst is continuously charged with the initialization voltage Vinit from the first period A to the second period B. Accordingly, the storage capacitor Cst can be sufficiently charged with the initialization voltage Vinit, and thus the first node voltage VN1 can be maintained at the initialization voltage Vinit.

To elaborate, during one horizontal period (1H) of the first period (A) and one horizontal period (2H) of the second period (B), that is, for a total of two horizontal periods, the first node (N1) ) is supplied with the initialization voltage (Vinit). Accordingly, the storage capacitor Cst can be sufficiently charged with the initialization voltage Vinit.

In this case, the data voltage (Vdata) of the previous stage is supplied to the second transistor (T2), the driving transistor (Tdr), and the fifth transistor (T5). Here, the data voltage (Vdata) of the previous stage is not the data voltage used by the driving transistor (Tdr) shown in FIG. 5 to control the current (Ioled) flowing to the organic light emitting diode (OLED).

Next, in the third period C, as shown in FIGS. 3 and 6, the low-level first scan signal SCAN(n) is transmitted to the second transistor T2 and the fifth transistor T5. is supplied, a high-level second scan signal (SCAN(n-1)) is supplied to the fourth transistor (T4) and the seventh transistor (T7), and a low-level third scan signal (SCAN(n+) 1)) is supplied to the third transistor (T3), and a high level emission signal (EM(n)) is supplied to the first transistor (T1) and the sixth transistor (T6).

Accordingly, as shown in FIG. 6, the second transistor (T2), the driving transistor (Tdr), the fifth transistor (T5), the third transistor (T3), the seventh transistor (T7), and The fourth transistor T4 is turned on, and the first transistor T1 and the sixth transistor T6 are both turned off. In this case, the driving transistor (Tdr) may be turned on by the first node voltage (VN1).

In addition, while the above process is performed, the data voltage (Vdata) supplied through the data line (DL) and the threshold voltage of the driving transistor (Tdr) are supplied to the first node (N1), and the storage capacitor ( The data voltage (Vdata) and the threshold voltage are charged to Cst).

That is, in the third period (C), the threshold voltage of the driving transistor (Tdr) and the data voltage (Vdata) are supplied to the first node (N1) for one horizontal period (1H), and the storage capacitor (Cst) is charged with the threshold voltage and the data voltage (Vdata).

Accordingly, the first node voltage (VN1) is the sum of the threshold voltage and the data voltage (Vdata) from the initialization voltage (Vinit) maintained in the first period (A) and the second period (B). It increases with the value (Vdata+Vth).

In order for the first node voltage (VN1) to be maintained at the threshold voltage and the data voltage (Vdata) in the third period (C), as described above, the initialization voltage (Vinit) is applied to the storage capacitor ( Cst) must be accurately charged. For this purpose, in the present invention, as described above, during one horizontal period (1H) of the first period (A) and one horizontal period (1H) of the second period (B), that is, a total of two horizontal periods The initialization voltage Vinit is supplied to the first node N1 during the period 2H.

Next, in the fourth period (D), as shown in FIGS. 3 and 7, the high-level first scan signal (SCAN(n)) is transmitted to the second transistor (T2) and the fifth transistor (T5). is supplied, a high-level second scan signal (SCAN(n-1)) is supplied to the fourth transistor (T4) and the seventh transistor (T7), and a low-level third scan signal (SCAN(n+) 1)) is supplied to the third transistor (T3), and a high level emission signal (EM(n)) is supplied to the first transistor (T1) and the sixth transistor (T6).

Accordingly, as shown in FIG. 7, only the third transistor T3 is turned on, and the first transistor T1, the second transistor T2, and the fourth to seventh transistors T4 to T7 are all turned on. It turns off.

In this case, the first node voltage VN1 is maintained at the voltage applied in the third period C.

Finally, in the fifth period (E), as shown in FIGS. 3 and 8, the high-level first scan signal (SCAN(n)) is transmitted to the second transistor (T2) and the fifth transistor (T5). ), a high-level second scan signal (SCAN(n-1)) is supplied to the fourth transistor (T4) and the seventh transistor (T7), and a high-level third scan signal (SCAN (n-1)) is supplied to the fourth transistor (T4) and the seventh transistor (T7). n+1)) is supplied to the third transistor T3, and a low-level emission signal EM(n) is supplied to the first transistor T1 and the sixth transistor T6.

Accordingly, as shown in FIG. 8, the first transistor (T1), the driving transistor (Tdr), and the sixth transistor (T6) are turned on, and the second to fifth transistors (T2 to T5) And the seventh transistor T7 is turned off.

In this case, because the first node voltage (VN1) is supplied to the gate of the driving transistor (Tdr), the driving transistor (Tdr) is also turned on.

Accordingly, current may be supplied to the organic light-emitting diode (OLED) through the first transistor (T1), the driving transistor (Tdr), and the sixth transistor (T6), and the organic light-emitting diode (OLED) Light of brightness corresponding to the current can be output.

In this case, the voltage applied to the gate of the driving transistor (Tdr) is the sum (Vdata + Vth) of the data voltage (Vdata) and the threshold voltage (Vth) of the driving transistor (Tdr). The voltage applied to the source is the first driving voltage (VDD). The current (Ioled) passing through the driving transistor (Tdr) is the threshold voltage (Vth) of the driving transistor (Tdr) at the difference voltage (Vgs) (=Vdata + Vth-VDD) between the gate and source of the driving transistor (Tdr). ) is proportional to the voltage minus (=Vdata+Vth-VDD-Vth).

That is, the current (Ioled) supplied to the organic light emitting diode (OLED) through the driving transistor (Tdr) can be expressed as [Equation 1] below.

In [Equation 1], k is a proportionality constant determined by various factors.

That is, the current (Ioled) supplied to the organic light emitting diode (OLED) through the driving transistor (Tdr) is determined by the data voltage (Vdata) and the first driving voltage (VDD), and the driving transistor (Tdr) ) is not determined by the threshold voltage (Vth).

In general, the driving transistor (Tdr) may deteriorate as the organic light emitting display device is used for a long time, and accordingly, the threshold voltage (Vth) of the driving transistor (Tdr) may change.

Additionally, the degree of deterioration of the driving transistor Tdr provided in the pixel 110 formed in the organic light emitting display panel 100 may vary due to various causes.

If the degree of deterioration of the driving transistors (Tdr) varies, the threshold voltages of the driving transistors (Tdr) also change.

When the threshold voltages of the driving transistors (Tdr) vary, even if the same data voltages (Vdata) are supplied to the driving transistors (Tdr), the current supplied to the organic light-emitting diodes (OLED) through the driving transistors (Tdr) changes. Sizes may vary. Accordingly, organic light emitting diodes (OLEDs) provided in pixels supplied with the same data voltage (Vdata) may output light of different brightness.

In order to solve the problem described above, the present invention is designed so that the current flowing through the driving transistor (Tdr) is not affected by the threshold voltage (Vth) of the driving transistor (Tdr).

That is, in the present invention, by the pixel structure as shown in FIG. 2 and the driving method described with reference to FIGS. 3 to 8, the size of the current (Ioled) passing through the driving transistor (Tdr) is [ As described in Equation 1, it is not affected by the threshold voltage (Vth) of the driving transistor (Tdr).

Therefore, according to the present invention, even if the driving transistors (Tdr) are deteriorated, a normal current corresponding to the data voltage (Vdata) can be supplied to the organic light emitting diode (OLED) in each pixel, and accordingly, the organic light emitting diode (OLED) OLED) can output light with brightness proportional to the data voltage (Vdata).

In particular, in the present invention, one end of the storage capacitor Cst, that is, the first node ( The initialization voltage (Vinit) is supplied to N1).

Therefore, even if the organic light emitting display device according to the present invention is driven at a high frequency, the initialization voltage Vinit can sufficiently charge the storage capacitor Cst, and accordingly, the data can be stored in the first node N1. The voltage (Vdata) and the threshold voltage (Vth) may be applied normally, and therefore, the driving transistor (Tdr) may transmit the current (Ioled) to the organic light emitting diode (OLED) according to the data voltage (Vdata). can be supplied.

Figure 9 is a graph for explaining the effect of the organic light emitting display device according to the present invention. In Figure 9, (a) shows the voltage (VN1) applied to the gate of the driving transistor when the initialization voltage is supplied for one horizontal period (1H) in a conventional organic light emitting display device, and (b) shows the voltage (VN1) applied to the gate of the driving transistor according to the present invention. Indicates the first node voltage (VN1) when the initialization voltage (Vinit) is supplied to the first node (N1) for two horizontal periods (2H) in the organic light emitting display device.

As described above, in a conventional organic light emitting display device, for example, as shown in (a) of FIG. 9, an initialization voltage of negative (-) polarity is applied to the driving transistor only during one horizontal period (1H). It can be applied to the gate of .

Since the one horizontal period (1H) is a period during which the data voltage is supplied to the data line, as the resolution of the organic light emitting display device increases or the organic light emitting display device is driven at a high frequency, the one horizontal period becomes shorter.

If the 1 horizontal period (1H) is too short and the initialization voltage is not sufficiently charged during the 1 horizontal period (1H), the initialization voltage (Vinit) having a negative (-) polarity cannot sufficiently charge the storage capacitor. . In this case, the voltage (X1) applied to the gate of the driving transistor and actually charged to the storage capacitor (Cst) may not reach the initialization voltage (Vinit). That is, in a conventional organic light emitting display device, the actual voltage (X1) charged in the storage capacitor (Cst) during one horizontal period (1H) is the initialization voltage (Vinit), as shown in (a) of FIG. It can be bigger than

Therefore, when the threshold voltage and data voltage of the driving transistor are supplied after the initialization voltage Vinit is charged in the storage capacitor Cst for one horizontal period, they are applied to the gate of the driving transistor and charge the storage capacitor. The actual voltage (Y1) may be greater than the sum of the threshold voltage and the data voltage (=Y =Vdata+Vth).

To elaborate, in a conventional organic light emitting display device, the voltage (X1) actually charged in the storage capacitor (Cst) before the threshold voltage and the data voltage are supplied is greater than the initialization voltage (Vinit). Therefore, after the voltage (X1) is charged, when the threshold voltage and the data voltage are supplied, the actual voltage (Y1) charged in the storage capacitor (Cst) is the sum of the threshold voltage and the data voltage (Y ) can be larger than

Accordingly, the difference voltage between the gate and source of the driving transistor may be different from the voltage intended by the data voltage, and therefore, light with a brightness that does not correspond to the data voltage may be output. In contrast, in the present invention, as shown in (b) of FIG. 9, in the first period (A) and the second period (B), the first node (N1) for two horizontal periods (2H) The initialization voltage (Vinit) is supplied. Accordingly, the initialization voltage Vinit can sufficiently charge the storage capacitor Cst.

Accordingly, the voltage (X2) applied to the gate of the driving transistor, that is, the first node (N1) and actually charged in the storage capacitor, may be the initialization voltage (Vinit).

Accordingly, after the initialization voltage Vinit is charged, when the threshold voltage Vth of the driving transistor Tdr and the data voltage Vdata are supplied in the third period C, the first node N1 The actual voltage (Y2) applied to and charged to the storage capacitor can accurately reach the sum of the threshold voltage and the data voltage (=Y = Vdata + Vth).

That is, according to the present invention, since the charging time of the initialization voltage (Vinit) can be maintained for two horizontal periods (2H), the first node voltage (VN1) can be maintained at the initialization voltage (Vinit). . In addition, since the threshold voltage (Vth) and the data voltage (Vdata) are supplied to the first node (N1) while the first node voltage (VN1) is maintained at the initialization voltage (Vinit), The first node voltage (VN1) can ultimately be maintained as the sum of the threshold voltage (Vth) and the data voltage (Vdata) (=Y = Vdata + Vth).

Accordingly, the driving transistor (Tdr) can supply a current (Ioled) that exactly corresponds to the data voltage (Vdata) to the organic light emitting diode (OLED).

Accordingly, the organic light emitting diode (OLED) can output light with a brightness corresponding to the data voltage (Vdata).

That is, according to the present invention, light with a brightness corresponding to the data voltage (Vdata) can be accurately output, and therefore, defects such as spots do not occur.

In particular, according to the present invention, since the current (Ioled) supplied to the organic light emitting diode (OLED) does not affect the threshold voltage (Vth) of the driving transistor (Tdr), the driving transistor (Tdr) is used for a long time. Therefore, even if the threshold voltage of the driving transistor (Tdr) changes, light with a brightness corresponding to the data voltage (Vdata) can be accurately output.

Those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing its technical idea or essential features. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

100: panel 200: gate driver
300: data driver 400: control unit

Claims (11)

An organic light emitting display panel including pixels including an organic light emitting diode and a pixel driver circuit that drives the organic light emitting diode; and
a driver that supplies data voltages to data lines provided in the organic light emitting display panel and scan signals to scan lines provided in the organic light emitting display panel;
The pixel driving circuit includes a driving transistor that controls the current supplied to the organic light emitting diode and a storage capacitor that charges the data voltage supplied from the driving unit and the threshold voltage of the driving transistor,
During a second horizontal period that is twice as long as the first horizontal period during which the data voltage is supplied to the data line, an initialization voltage that initializes a first node connected to the gate of the driving transistor is charged in the storage capacitor,
In a first period, the initialization voltage is supplied to the first node for one horizontal period,
In a second period, the initialization voltage is supplied to the first node for one horizontal period,
In the third period, the threshold voltage of the driving transistor and the data voltage are supplied to the first node for one horizontal period,
In the fourth period, during one horizontal period, the voltage of the first node is maintained at the threshold voltage of the driving transistor and the data voltage,
In the fifth period, the driving transistor passes a current corresponding to the data voltage to the organic light emitting diode for one horizontal period. According to claim 1,
The pixel driving circuit is,
the driving transistor;
The storage capacitor has one end connected to the first node and the other end connected to a first driving voltage line that supplies a first driving voltage to the organic light emitting diode; and
An organic light emitting display device connected to the driving transistor and the storage capacitor and including seven transistors for varying the voltage charged in the storage capacitor. delete According to claim 1,
An organic light emitting display device in which the current supplied to the organic light emitting diode through the driving transistor in the fifth period is not affected by the threshold voltage of the driving transistor. According to claim 1,
An organic light emitting display device in which the current supplied to the organic light emitting diode through the driving transistor is not affected by the threshold voltage of the driving transistor. According to claim 1,
The pixel driving circuit is,
the driving transistor having a first terminal and a second terminal connected to a first driving voltage line that supplies a first driving voltage to the organic light emitting diode;
The storage capacitor has one end connected to a first node connected to the gate of the driving transistor and the other end connected to the first driving voltage line;
at least one emission unit that is turned on or off according to an emission signal transmitted from the driver to control light emission timing of the organic light emitting diode;
a switching unit connected between the driving transistor and the data line, turned on according to a first scan signal and a third scan signal transmitted from the driving unit, and charging the storage capacitor with the data voltage and the threshold voltage; and
An organic light emitting display device comprising an initialization unit that is turned on or off according to a second scan signal transmitted from the driver and charges the storage capacitor with the initialization voltage. According to claim 6,
In a first period, during one horizontal period, the initialization voltage is supplied to a first node between the storage capacitor and the gate of the driving transistor through the initialization charger,
In a second period, the initialization voltage is supplied to the first node through the initialization charging unit for one horizontal period,
In the third period, during one horizontal period, the threshold voltage of the driving transistor and the data voltage are supplied to the first node through the switching unit and the driving transistor,
In the fourth period, during one horizontal period, the voltage of the first node is maintained at the threshold voltage of the driving transistor and the data voltage,
In the fifth period, an organic light emitting display device in which a current corresponding to the data voltage is supplied to the organic light emitting diode through the driving transistor and the emission unit for one horizontal period. According to claim 6,
The emission unit is,
a first transistor whose gate is connected to the driver, a first terminal connected to the other terminal of the storage capacitor, and a second terminal connected to the first terminal of the driving transistor; and
A sixth transistor whose gate is connected to the driver, a first terminal connected to the second terminal of the driving transistor, and a second terminal connected to the organic light emitting diode,
The switching unit,
a second transistor whose gate is connected to the driver, a first terminal connected to the data line, and a second terminal connected to the first terminal of the driving transistor;
a third transistor whose gate is connected to the driver and whose second terminal is connected to the first node; and
A fifth transistor whose gate is connected to the driver, a first terminal connected to the first terminal of the third transistor, and a second terminal connected to the second terminal of the driving transistor,
The initialization unit,
a fourth transistor whose gate is connected to the driver, whose first terminal is supplied with the initialization voltage, and whose second terminal is connected to the first node; and
An organic light emitting display including a seventh transistor whose gate is connected to the driver, a first terminal connected to the first terminal of the fourth transistor, and a second terminal connected to the second terminal of the sixth transistor. Device. An organic light emitting display panel including pixels including an organic light emitting diode and a pixel driver circuit that drives the organic light emitting diode; and
a driver that supplies data voltages to data lines provided in the organic light emitting display panel and scan signals to scan lines provided in the organic light emitting display panel;
The pixel driving circuit includes a driving transistor that controls the current supplied to the organic light emitting diode and a storage capacitor that charges the data voltage supplied from the driving unit and the threshold voltage of the driving transistor,
During a second horizontal period that is twice as long as the first horizontal period during which the data voltage is supplied to the data line, an initialization voltage that initializes a first node connected to the gate of the driving transistor is charged in the storage capacitor,
The pixel driving circuit is,
The driving transistor having a first terminal and a second terminal connected to a first driving voltage line that supplies a first driving voltage to the organic light emitting diode,
The storage capacitor, one end of which is connected to the gate of the driving transistor and the other end of which is connected to the first driving voltage line,
A first transistor whose gate is connected to the driver, a first terminal connected to the other terminal of the storage capacitor, and a second terminal connected to the first terminal of the driving transistor,
a second transistor whose gate is connected to the driver, a first terminal connected to the data line, and a second terminal connected to the first terminal of the driving transistor;
A third transistor, the gate of which is connected to the driving unit, the first terminal of which is connected to the second terminal of the driving transistor, and the second terminal of which is connected to the gate of the driving transistor,
A fourth transistor, the gate of which is connected to the driving unit, the initialization voltage supplied to the first terminal, and the second terminal connected to the gate of the driving transistor,
A fifth transistor, the gate of which is connected to the driver, the first terminal of which is connected to the first terminal of the third transistor, and the second terminal of which is connected to the second terminal of the driving transistor,
a sixth transistor whose gate is connected to the driving unit, a first terminal connected to the second terminal of the driving transistor, and a second terminal connected to the organic light emitting diode; and
An organic light emitting display including a seventh transistor whose gate is connected to the driver, a first terminal connected to the first terminal of the fourth transistor, and a second terminal connected to the second terminal of the sixth transistor. Device.
According to clause 9,
The first transistor and the sixth transistor are turned on or off by an emission signal transmitted from the driver,
The second transistor and the fifth transistor are turned on or off by the first scan signal transmitted from the driver,
The fourth transistor and the seventh transistor are turned on or off by the second scan signal transmitted from the driver,
The third transistor is turned on or off by a third scan signal transmitted from the driver. According to clause 9,
In a first period, during one horizontal period, the initialization voltage is supplied to a first node between the one end of the storage capacitor and the gate of the driving transistor through the fourth transistor,
In a second period, the initialization voltage is supplied to the first node through the fourth transistor for one horizontal period,
In the third period, during one horizontal period, the threshold voltage of the driving transistor and the data voltage are supplied to the first node through the second transistor, the driving transistor, the fifth transistor, and the third transistor,
In the fourth period, during one horizontal period, the voltage of the first node is maintained at the threshold voltage of the driving transistor and the data voltage,
In the fifth period, an organic light emitting display device in which a current corresponding to the data voltage is supplied to the organic light emitting diode through the first transistor, the driving transistor, and the sixth transistor during one horizontal period.

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