KR102496448B1 - Pixel circuit, light emitting display apparatus including pixel circuit, and operating methods thereof - Google Patents

Abstract

Disclosed are a pixel circuit, a light emitting display apparatus including a pixel circuit, and operating methods thereof. The disclosed pixel circuit comprises: a light emitting element based on a light emitting diode; a driving transistor for controlling the drive of the light emitting element; a first switching transistor connected to the driving transistor; a second switching transistor connected to the first switching transistor; a third switching transistor connected to the driving transistor; a fourth switching transistor connected to the second switching transistor; a fifth switching transistor connected between the driving transistor and the light emitting element; a first capacitor connected between the first switching transistor and the third switching transistor; and a second capacitor connected between the second switching transistor and the fourth switching transistor. The pixel circuit can be configured to be able to perform the threshold voltage compensation and mobility compensation of the driving transistor.

Description

Pixel circuit, light emitting display device including pixel circuit, and operation method thereof

The present invention relates to display technology, and more particularly, to a pixel circuit, a light emitting display device including the pixel circuit, and an operating method thereof.

With the rapid development of the information society, the demand for display devices for displaying images is increasing in various forms, such as liquid crystal display apparatus, plasma display apparatus, and organic or inorganic light emitting display devices. Various types of display devices, such as organic light emitting display apparatuses, are being utilized.

A light emitting diode used in an organic light emitting display or an inorganic light emitting display among various display devices is a self-emitting device that emits light by itself and has characteristics of high luminance and low operating voltage. In addition, the organic and inorganic light emitting display devices have advantages in that they have a high contrast ratio, are easy to implement in an ultra-thin form, have no afterimage, no restriction on a viewing angle, and can be stably driven even at low temperatures due to a very short response time.

However, when a difference in characteristics, such as a threshold voltage and mobility, occurs between driving transistors formed in a plurality of pixels of an organic or inorganic light emitting display device, the amount of current driving these light emitting elements (OLED) is affected. A change occurs, resulting in a luminance difference between pixels. That is, a driving current supplied to the light emitting elements OLED is not constant due to a characteristic deviation between the driving transistors, and thus, a problem such as non-uniform luminance may occur. In particular, in the case of a pixel circuit in which the driving circuit is based on an oxide TFT, deviations in mobility characteristics as well as threshold voltage deviations of driving transistors may occur during the manufacturing process, and deviations in characteristics due to deterioration due to driving may also occur. Since this may occur, a technology capable of compensating for such characteristic deviation is required.

A technical problem to be achieved by the present invention is to provide a pixel circuit capable of easily performing mobility compensation as well as threshold voltage compensation of a driving transistor, and also easily performing a data input operation.

In addition, a technical problem to be achieved by the present invention is to provide a light emitting display device including the pixel circuit described above.

In addition, a technical problem to be achieved by the present invention is to provide an operating method (driving method) of the pixel circuit and the light emitting display device.

The problem to be solved by the present invention is not limited to the problems mentioned above, and other problems not mentioned will be understood by those skilled in the art from the description below.

According to one embodiment of the present invention, an organic or inorganic light emitting device (OLED); a driving transistor for controlling driving of the light emitting element, having a driving gate terminal, a first driving terminal to which a first power supply voltage is applied, and a second driving terminal electrically connected to the light emitting element; a first switching transistor connected to the driving transistor and having a first gate terminal to which a first scan signal is applied, a 1-1 terminal to which a reference voltage is applied, and a 1-2 terminal electrically connected to the driving gate terminal; a second switching transistor having a second gate terminal to which a second scan signal is applied, a 2-1 terminal to which a data voltage is applied, and a 2-2 terminal electrically connected to the 1-2 terminal; A third gate terminal to which a third scan signal is applied, a 3-1 terminal electrically connected to the 1-2 terminal and the 2-2 terminal, and a 3-2 terminal electrically connected to the second driving terminal a third switching transistor having; A fourth gate terminal to which the second scan signal is applied, a 4-1 terminal electrically connected to the second driving terminal and the 3-2 terminal, and a 4-2 disposed spaced apart from the 4-1 terminal. a fourth switching transistor having a terminal; a fifth switching transistor connected between the driving transistor and the OLED and having a fifth gate terminal to which an emission control signal is applied, a 5-1 terminal connected to the driving transistor, and a 5-2 terminal connected to the OLED; a first capacitor connected between the first switching transistor and the third switching transistor and having a 1-1 electrode connected to the 1-2 terminal and a 1-2 electrode connected to the 3-1 terminal; and a 2-1 electrode connected to the 2-2 terminal and the 3-1 terminal, the 3-2 terminal and the 4-1 terminal connected between the second switching transistor and the fourth switching transistor. A pixel circuit including a second capacitor having a 2-2 electrode connected to the terminal is provided.

At least one of the first to fifth switching transistors and the driving transistor may be an oxide thin film transistor.

The pixel circuit may be configured to perform threshold voltage compensation and mobility compensation of the driving transistor.

The pixel circuit may be a circuit for constituting a simultaneous emission type display device.

According to another embodiment of the present invention, as a method of operating the pixel circuit described above, the first and third switching transistors are turned on and the second and fourth switching transistors are turned off. a threshold voltage compensating step of storing a voltage corresponding to the threshold voltage of the driving transistor in one capacitor; The data voltage is stored in the second capacitor by turning off the first and third switching transistors, turning on the second and fourth switching transistors, and applying the data voltage to the second switching transistor. a data input step of storing a voltage corresponding to the voltage; By turning on the first switching transistor in a state where the second to fourth switching transistors are turned off, the sum of the voltages stored in the first and second capacitors is proportional to the mobility of the driving transistor. A mobility compensation step of compensating with a compensation voltage; and a light emitting step of emitting light from the light emitting element.

The method may further include an initialization step of resetting the first and second capacitors by turning on the first to fourth switching transistors before the threshold voltage compensating step.

Between the data input step and the mobility compensating step, a stabilization step of stabilizing the voltage stored in each of the first and second capacitors by turning off the first to fourth switching transistors may be further included. .

Between the mobility compensation step and the light emitting step, a holding step of maintaining a state in which the first to fifth switching transistors are turned off may be further included.

A plurality of data lines to which signals corresponding to the data voltages are applied may be provided, and the data input step may be performed on the plurality of data lines.

According to another embodiment of the present invention, a light emitting device; a driving transistor for controlling driving of the light emitting element, having a driving gate terminal, a first driving terminal to which a first power supply voltage is applied, and a second driving terminal electrically connected to the light emitting element; a first switching transistor connected to the driving transistor and having a first gate terminal to which a first scan signal is applied, a 1-1 terminal to which a reference voltage is applied, and a 1-2 terminal electrically connected to the driving gate terminal; a second switching transistor having a second gate terminal to which a second scan signal is applied, a 2-1 terminal to which a data voltage is applied, and a 2-2 terminal electrically connected to the 1-2 terminal; A third gate terminal to which a third scan signal is applied, a 3-1 terminal electrically connected to the 1-2 terminal and the 2-2 terminal, and a 3-2 terminal electrically connected to the second driving terminal a third switching transistor having; A 4-1 terminal electrically connected to a fourth gate terminal to which a fourth scan signal is applied, the second driving terminal, and the 3-2 terminal, and a 4-2 terminal spaced apart from the 4-1 terminal A fourth switching transistor having a; A fifth switching transistor connected between the driving transistor and the light emitting element and having a fifth gate terminal to which a light emitting control signal is applied, a 5-1 terminal connected to the driving transistor, and a 5-2 terminal connected to the light emitting element ; A sixth gate terminal connected between a power supply unit generating the first power supply voltage and the driving transistor, to which the fourth scan signal or an inverse signal of the fourth scan signal is applied, and a sixth-connected power supply unit a sixth switching transistor having a first terminal and a 6-2 terminal connected to the first driving terminal; a first capacitor connected between the first switching transistor and the third switching transistor and having a 1-1 electrode connected to the 1-2 terminal and a 1-2 electrode connected to the 3-1 terminal; and a 2-1 electrode connected to the 2-2 terminal and the 3-1 terminal, the 3-2 terminal and the 4-1 terminal connected between the second switching transistor and the fourth switching transistor. A pixel circuit including a second capacitor having a 2-2 electrode connected to the terminal is provided.

At least one of the first to sixth switching transistors and the driving transistor may be an oxide thin film transistor.

When the fourth switching transistor is in an on state, the sixth switching transistor may be in an off state, and when the fourth switching transistor is in an off state, the sixth switching transistor is on (ON) state.

The pixel circuit may be configured to perform threshold voltage compensation and mobility compensation of the driving transistor.

The pixel circuit may be a circuit for constructing a sequential emission type display device.

According to another embodiment of the present invention, as a method of operating the pixel circuit described above, by turning on the first, third and sixth switching transistors and turning off the second and fourth switching transistors. , a threshold voltage compensating step of storing a voltage corresponding to the threshold voltage of the driving transistor in the first capacitor; By turning off the first, third and sixth switching transistors, turning on the second and fourth switching transistors, and applying the data voltage to the second switching transistor, the second capacitor a data input step of storing a voltage corresponding to the data voltage to; By turning on the first switching transistor in a state where the second to fourth switching transistors are turned off and the sixth switching transistor is turned on, the voltage stored in the first and second capacitors is reduced. a mobility compensation step of compensating the sum with a compensation voltage proportional to the mobility of the driving transistor; and a light emitting step of emitting light from the light emitting element.

Before the threshold voltage compensating step, by turning on the first, third and fourth switching transistors and turning off the second and sixth switching transistors, the first and second capacitors are initialized ( An initialization step of resetting may be further included.

Between the data input step and the mobility compensating step, a stabilization step of stabilizing the voltage stored in each of the first and second capacitors by turning off the first to fourth switching transistors may be further included. .

Between the mobility compensating step and the light emitting step, a holding step of turning off the first to fifth switching transistors and maintaining an turned on state of the sixth switching transistor may be further included. can

According to another embodiment of the present invention, a light emitting diode-based light emitting display device including the pixel circuit according to the above embodiments is provided.

According to another embodiment of the present invention, a method of operating a light emitting display device based on a light emitting diode including the method of operating a pixel circuit according to the above embodiments is provided.

According to the embodiments of the present invention, it is possible to provide a pixel circuit that can easily perform mobility compensation as well as threshold voltage compensation of a driving transistor, and also easily perform a data input operation and an operating method thereof. there is. Using the pixel circuit and its operating method according to the embodiments, it is possible to effectively and accurately compensate for the deviation/dispersion of electrical characteristics (threshold voltage, mobility) of the driving transistors, and to improve a problem such as luminance non-uniformity to achieve a uniform picture quality. can be implemented.

By applying the pixel circuit and its operating method according to embodiments of the present invention, a light emitting diode-based light emitting display device having excellent picture quality uniformity and high reliability can be implemented.

1 is a circuit diagram showing a pixel circuit according to an exemplary embodiment of the present invention.
2 is a diagram for explaining an operating method of a pixel circuit according to an exemplary embodiment of the present invention.
FIG. 3A is a circuit diagram showing an operating state of a pixel circuit in an initialization stage of FIG. 2 .
3B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the initialization step.
FIG. 4A is a circuit diagram showing an operating state of a pixel circuit in the threshold voltage compensation step of FIG. 2 .
4B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the threshold voltage compensating step.
FIG. 5A is a circuit diagram showing an operating state of a pixel circuit in a data input stage of FIG. 2 .
5B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the data input step.
FIG. 6A is a circuit diagram showing an operating state of a pixel circuit in a stabilization stage of FIG. 2 .
6B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the stabilization step.
FIG. 7A is a circuit diagram showing an operating state of a pixel circuit in a mobility compensation step of FIG. 2 .
7B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the mobility compensation step.
FIG. 8A is a circuit diagram showing an operating state of a pixel circuit in a holding step of FIG. 2 .
8B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the holding step.
FIG. 9A is a circuit diagram showing an operating state of a pixel circuit in a light emitting stage of FIG. 2 .
9B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the light emitting step.
10 is a circuit diagram showing a pixel circuit according to another exemplary embodiment of the present invention.
11 is a diagram for explaining an operating method of a pixel circuit according to another exemplary embodiment of the present invention.
FIG. 12A is a circuit diagram showing an operating state of a pixel circuit in an initialization stage of FIG. 11 .
12B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the initialization step.
13A is a circuit diagram showing an operating state of a pixel circuit in a threshold voltage compensation step of FIG. 11 .
13B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the threshold voltage compensating step.
14A is a circuit diagram showing an operating state of a pixel circuit in a data input stage of FIG. 11 .
14B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the data input step.
FIG. 15A is a circuit diagram showing an operating state of a pixel circuit in a stabilization stage of FIG. 11 .
15B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the stabilization step.
16A is a circuit diagram showing an operating state of a pixel circuit in a mobility compensation step of FIG. 11 .
16B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the mobility compensation step.
17A is a circuit diagram showing an operating state of a pixel circuit in a holding step of FIG. 11 .
17B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the holding step.
FIG. 18A is a circuit diagram showing an operating state of a pixel circuit in a light emission stage of FIG. 11 .
18B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the light emitting step.
19 to 22 are graphs showing results obtained by verifying driving characteristics of the pixel circuit having the configuration of FIG. 1 using simulation program with integrated circuit emphasis (SPICE).
23 to 26 are graphs showing results of verifying driving characteristics of the pixel circuit having the configuration of FIG. 10 using SPICE simulation.

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

Embodiments of the present invention to be described below are provided to more clearly explain the present invention to those skilled in the art, and the scope of the present invention is not limited by the following examples, Embodiments may be modified in many different forms.

Terms used in this specification are used to describe specific embodiments and are not intended to limit the present invention. Terms in the singular form used herein may include plural forms unless the context clearly indicates otherwise. Also, as used herein, the terms "comprise" and/or "comprising" specify the presence of the stated shape, step, number, operation, member, element, and/or group thereof. and does not exclude the presence or addition of one or more other shapes, steps, numbers, operations, elements, elements and/or groups thereof. In addition, the term “connection” used in this specification means not only direct connection of certain members, but also a concept including indirect connection by intervening other members between the members.

In addition, when a member is said to be located “on” another member in the present specification, this includes not only a case where a member is in contact with another member, but also a case where another member exists between the two members. As used herein, the term “and/or” includes any one and all combinations of one or more of the listed items. In addition, terms of degree such as "about" and "substantially" used in the present specification are used in a range of values or degrees or meanings close thereto, taking into account inherent manufacturing and material tolerances, and are used to help the understanding of the present application. Exact or absolute figures provided for this purpose are used to prevent undue exploitation by infringers of the stated disclosure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The size or thickness of areas or parts shown in the accompanying drawings may be slightly exaggerated for clarity of the specification and convenience of description. Like reference numbers indicate like elements throughout the detailed description.

1 is a circuit diagram showing a pixel circuit according to an exemplary embodiment of the present invention.

Referring to FIG. 1 , a pixel circuit according to an embodiment of the present invention may include a light emitting device and a driving transistor DRT for controlling driving of the light emitting device. The light emitting device may include an organic light emitting device or an inorganic light emitting device. The organic light emitting diode OLED may include an anode, a cathode, and an organic light emitting layer disposed therebetween. The organic light emitting diode (OLED) may be referred to as one light emitting cell (light emitting unit). All known organic light emitting diode structures may be applied to organic light emitting diodes (OLEDs) according to embodiments of the present invention. The inorganic light emitting device has a structure similar to that of the organic light emitting device except that an inorganic light emitting layer is disposed between an anode and a cathode. Hereinafter, the present invention is described by exemplifying an organic light emitting device, but an inorganic light emitting device applied instead of an organic light emitting device is also included in an embodiment of the present invention.

The driving transistor DRT includes a gate terminal (hereinafter, a driving gate terminal) DG1, a first terminal (hereinafter, a first driving terminal) DE1, and a second terminal (hereinafter, a second driving terminal) DE2. can do. The first power supply voltage ELVDD may be applied to the first driving terminal DE1, and the second driving terminal DE2 may be electrically connected to the organic light emitting diode OLED. The second driving terminal DE2 may be electrically connected to the anode side of the organic light emitting diode OLED. The first driving terminal DE1 may be a source terminal (electrode), and the second driving terminal DE2 may be a drain terminal (electrode).

The pixel circuit may include first to fifth switching transistors T1 to T5. The first switching transistor T1 may be connected to the driving transistor DRT. The first switching transistor T1 is connected to the first gate terminal G1 to which the first scan signal SCAN1 is applied, the 1-1 terminal E11 to which the reference voltage VREF is applied, and the driving gate terminal DG1. It may include electrically connected first and second terminals E12. The 1-1 terminal E11 may be a source terminal, and the 1-2 terminal E12 may be a drain terminal.

The second switching transistor T2 includes a second gate terminal G2 to which the second scan signal SCAN2 is applied, a 2-1 terminal E21 to which the data voltage VDATA is applied, and a 1-2 terminal E12 to which the data voltage VDATA is applied. ) may include a 2-2 terminal E22 electrically connected to the terminal. The 2-1 terminal E21 may be a source terminal, and the 2-2 terminal E22 may be a drain terminal.

The third switching transistor T3 is a third gate terminal G3 to which the third scan signal SCAN3 is applied and electrically connected to the 1-2 terminals E12 and 2-2 terminals E22. A 3-2 terminal E32 electrically connected to the first terminal E31 and the second driving terminal DE2 may be included. The 3-1 terminal E31 may be a source terminal, and the 3-2 terminal E32 may be a drain terminal or vice versa.

The fourth switching transistor T4 is a 4-1 electrically connected to the fourth gate terminal G4 to which the second scan signal SCAN2 is applied, the second driving terminal DE2, and the 3-2 terminal E32. A terminal E41 and a 4-2 terminal E42 spaced apart from the 4-1 terminal E41 may be included. The 4-2 terminal E42 may be grounded. The 4-1 terminal E41 may be a source terminal, and the 4-2 terminal E42 may be a drain terminal.

The fifth switching transistor T5 may be connected between the driving transistor DRT and the organic light emitting diode OLED. The fifth switching transistor T5 is connected to the fifth gate terminal G5 to which the emission control signal EM is applied, the 5-1 terminal E51 connected to the driving transistor DRT, and the organic light emitting diode OLED. 5-2 terminal (E52) may be included. The 5-1 terminal E51 may be connected to the second driving terminal DE2, and the 5-2 terminal E52 may be connected to the anode of the organic light emitting diode OLED. The 5-1 terminal E51 may be a source terminal, and the 5-2 terminal E52 may be a drain terminal.

Also, the pixel circuit may further include first and second capacitors C1 and C2. The first capacitor C1 may be connected between the first switching transistor T1 and the third switching transistor T3. The first capacitor C1 may include a 1-1 electrode e11 connected to the 1-2 terminal E12 and a 1-2 electrode e12 connected to the 3-1 terminal E31. A predetermined first dielectric layer may be disposed between the 1-1 electrode e11 and the 1-2 electrode e12.

The second capacitor C2 may be connected between the second switching transistor T2 and the fourth switching transistor T4. The second capacitor C2 includes the 2-1 electrode e21 connected to the 2-2 terminal E22 and the 3-1 terminal E31, the 3-2 terminal E32 and the 4-1 terminal ( A 2-2 electrode e22 connected to E41) may be included. A predetermined second dielectric layer may be disposed between the 2-1 electrode e21 and the 2-2 electrode e22.

The pixel circuit may include first to fifth nodes N1 to N5.

The first node N1 may be disposed between the 1-2 terminal E12 and the 1-1 electrode e11. Also, the first node N1 may be disposed between the first and second terminals E12 and the driving gate terminal DG1.

The second node N2 may be disposed between the 2-2 terminal E22 and the 1-2 electrode e12. Also, the second node N2 can be said to be disposed between the 2-2 terminal E22 and the 2-1 electrode e21.

The third node N3 is disposed between the first node N1 and the second node N2, and may be disposed between the 3-1 terminal E31 and the 1-2 electrode e12. Also, the third node N3 can be said to be disposed between the 3-1 terminal E31 and the 2-2 terminal E22.

The fourth node N4 may be disposed between the 3-2 terminal E32 and the second driving terminal DE2. Also, the fourth node N4 may be disposed between the second driving terminal DE2 and the 5-1 terminal E51.

The fifth node N5 may be disposed between the 2-2 electrode e22 and the 4-1 terminal E41. Also, the fifth node N5 may be disposed between the fourth node N4 and the 5-1 terminal E51.

In addition, the arrangement of the elements DRT, T1 to T5, C1, and C2 of the pixel circuit and the nodes N1 to N5 and the connection relationship between them may be as shown in FIG. 1 .

Meanwhile, the second power supply voltage ELVSS may be applied to an end (ie, cathode) of the organic light emitting diode OLED. The first power supply voltage ELVDD may be a high potential voltage (high potential driving voltage or high potential pixel voltage), and the second power supply voltage ELVSS may be a low potential voltage (low potential driving voltage or low potential pixel voltage). there is. For example, the second power supply voltage ELVSS may be a ground voltage.

The pixel circuit according to the exemplary embodiment shown in FIG. 1 may be a circuit for constructing a 'simultaneous emission type display device'. That is, the pixel circuit of FIG. 1 may be a circuit for constructing a simultaneous emission type display device in which a plurality of pixel areas simultaneously emit light. Also, at least one of the first to fifth switching transistors T1 to T5 and the driving transistor DRT may be, for example, an oxide thin film transistor. All of the first to fifth switching transistors T1 to T5 and the driving transistor DRT may be oxide thin film transistors. In this case, it can be said that the pixel circuit has a circuit configuration based on an oxide thin film transistor. However, in some cases, at least one of the first to fifth switching transistors T1 to T5 and the driving transistor DRT may be a transistor other than an oxide thin film transistor. The pixel circuit according to an embodiment of the present invention may be configured to perform threshold voltage compensation and mobility compensation of the driving transistor DRT.

2 is a diagram (driving waveform diagram) for explaining an operating method (driving method) of a pixel circuit according to an embodiment of the present invention. This embodiment is an operating method of the pixel circuit described in FIG. 1 .

Referring to FIG. 2 , a method of operating a pixel circuit according to an embodiment of the present invention includes an initialization step (S11), a threshold voltage compensation step (S12), a data input step (S13), a stabilization step (S14), and a mobility compensation step. (S15), a holding step (S16), and a light emitting step (S17) may be included. The threshold voltage compensation step ( S12 ), the data input step ( S13 ), the mobility compensation step ( S15 ), and the light emitting step ( S17 ) may be substantially (or alternatively) essential steps. The initialization step ( S11 ), the stabilization step ( S14 ) and the holding step ( S16 ) may be omitted or modifiable steps according to circumstances.

Hereinafter, with reference to FIGS. 3A to 9B , the aforementioned initialization step (S11), threshold voltage compensation step (S12), data input step (S13), stabilization step (S14), mobility compensation step (S15), holding Each of the step S16 and the light emitting step S17 will be described in detail.

FIG. 3A is a circuit diagram showing an operating state of a pixel circuit in an initialization step S11 of FIG. 2 . 3B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the initialization step (S11).

3A and 3B, the first and second capacitors C1 and C2 are reset by turning on the first to fourth switching transistors T1 to T4 in the initialization step S11. can do. Signals SCAN1 , SCAN2 , and SCAN3 may all be applied as high, and as a result, all of the first to fourth switching transistors T1 to T4 may be turned on. The upper voltage of the first capacitor C1 may be V _REF (ie, VREF: reference voltage), and the lower voltage of the first capacitor C1 (ie, the voltage at the left end of C2) and the second capacitor C2 All of the voltages at the right end of may be initialized to OV [ie, GND (ground)]. Accordingly, the voltage stored in the first capacitor C1 may be V _REF , and the voltage stored in the second capacitor C2 may be 0 V. At this time, the fifth switching transistor T5 may be in an off state.

FIG. 4A is a circuit diagram showing an operating state of a pixel circuit in the threshold voltage compensating step ( S12 ) of FIG. 2 . 4B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the threshold voltage compensating step (S12).

4A and 4B, in the threshold voltage compensating step (S12), the first and third switching transistors T1 and T3 are turned on, and the second and fourth switching transistors T2 and T4 are turned off. By turning it OFF, the voltage V _{TH_DRT} corresponding to the threshold voltage of the driving transistor DRT can be stored in the first capacitor C1. The SCAN1 and SCAN3 signals may be applied high and the SCAN2 signal low, and as a result, the first and third switching transistors T1 and T3 are turned on, and the second and the fourth switching transistors T2 and T4 may be turned off. The upper voltage of the first capacitor C1 may be maintained at VREF, and the lower voltage of the first capacitor C1 may be charged up to V _REF - V _{TH_DRT} . Here, V _{TH_DRT} may be a threshold voltage of the driving transistor DRT. Accordingly, the voltage V _{TH_DRT} corresponding to the threshold voltage of the driving transistor DRT may be stored in the first capacitor C1.

FIG. 5A is a circuit diagram showing an operating state of a pixel circuit in the data input step ( S13 ) of FIG. 2 . 5B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the data input step (S13).

5A and 5B, in the data input step S13, the first and third switching transistors T1 and T3 are turned off, and the second and fourth switching transistors T2 and T4 are turned on ( ON), and by applying the data voltage VDATA to the second switching transistor T2, the voltage corresponding to the data voltage VDATA (that is, the voltage indicated as V _DATA ) is stored in the second capacitor C2. can make it The SCAN2 signal may be high, and the SCAN1 and SCAN3 signals may be applied low, and as a result, the second and fourth switching transistors T2 and T4 are turned on, and the first and the third switching transistors T1 and T3 may be turned off. V _DATA may be applied to the left side of the second capacitor C2, and 0 V (ie, GND) may be applied to the right side of the second capacitor C2. At this time, in order for V _DATA to be accurately charged in the second capacitor C2, there should be no effect of ELVDD, so ELVDD can be lowered to GND (OV).

A display device including the pixel circuit of this embodiment may be a simultaneous emission type display device. The simultaneous emission type display device may include a plurality of data lines (vertical lines) to which signals corresponding to data voltages are applied, and the above-described data input operation S13 may be performed on the plurality of data lines. . That is, the data input step (S13) may be performed as many times as the number of the plurality of data lines.

FIG. 6A is a circuit diagram showing an operating state of a pixel circuit in the stabilization step ( S14 ) of FIG. 2 . 6B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the stabilization step (S14).

6A and 6B, by turning off the first to fourth switching transistors T1 to T4 in the stabilization step S14, the voltages stored in the first and second capacitors C1 and C2, respectively, are reduced. can be stabilized. In this step (S14), the SCAN1, SCAN2, and SCAN3 signals may all be applied as low.

FIG. 7A is a circuit diagram showing an operating state of a pixel circuit in the mobility compensation step ( S15 ) of FIG. 2 . 7B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the mobility compensation step (S15).

7A and 7B, in the mobility compensation step (S15), the first switching transistor T1 is turned on while the second to fourth switching transistors T2 to T4 are turned off. , the sum of the voltages stored in the first and second capacitors C1 and C2 is converted to a compensation voltage proportional to the mobility μ _{n_DRT} of the driving transistor DRT [ie, ΔV(μ _{n_DRT} , t, V _DATA )] Compensation (correction) can be made. The SCAN1, SCAN2, and SCAN3 signals may all be applied as low, and then only the SCAN1 signal may be applied as high. When the SCAN1 signal is applied as high, a current proportional to V _DATA + V _{TH_DRT} , which is the voltage between the gate and source of the driving transistor DRT, and the mobility flows, and the first and second capacitors C1 and C2 The sum of the stored voltages may decrease by ΔV (μ _{n_DRT} , t, V _DATA ). Since ΔV (μ _{n_DRT} , t, V _DATA ) in this step is a value affected not only by mobility but also by V _DATA , the characteristic that mobility varies according to voltage can be reflected in the mobility compensation process. ΔV (μ _{n_DRT} , t, V _DATA ) may increase as the mobility μ _{n_DRT} of the driving transistor DRT increases, as the mobility compensation time t increases, and as V _DATA increases.

FIG. 8A is a circuit diagram showing an operating state of the pixel circuit in the holding step ( S16 ) of FIG. 2 . 8B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the holding step (S16).

Referring to FIGS. 8A and 8B , in the holding step S16 , a state in which the first to fifth switching transistors T1 to T5 are turned off may be maintained (ie, holding) for a predetermined time. In order to adjust the emission time (ie, emission ratio), a time interval may be provided until the EM signal (emission control signal) is applied as high.

FIG. 9A is a circuit diagram showing an operating state of a pixel circuit in the light emitting step ( S17 ) of FIG. 2 . 9B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the light emitting step (S17).

Referring to FIGS. 8A and 8B , the organic light emitting diode (OLED) may emit light in the light emitting step ( S17 ). The OLED may emit light using the gate-source voltage of the driving transistor DRT stored through the previous steps. At this time, the current flowing through the organic light emitting diode (OLED), that is, I _OLED may be defined as in Equation 1 below.

In Equation 1 above, μ _{n_DRT} represents the mobility of the driving transistor DRT, V _DATA represents a data voltage, t represents a mobility compensation time, and ΔV (μ _{n_DRT} , t, V _DATA ) represents a compensation voltage where C _ox represents the capacitance of the gate insulating film of the driving transistor, W represents the channel width of the driving transistor, and L represents the channel length of the driving transistor.

As the mobility μ _{n_DRT} of the driving transistor DRT increases, the voltage to be corrected (reduced) increases, and thus the final driving voltage may decrease. Accordingly, a current error due to a difference in mobility may be corrected.

10 is a circuit diagram showing a pixel circuit according to another exemplary embodiment of the present invention.

Referring to FIG. 10 , the pixel circuit according to the present exemplary embodiment may include an organic light emitting diode (OLED) and a driving transistor (DRT) for controlling driving of the organic light emitting diode (OLED). The organic light emitting diode (OLED) may include an anode, a cathode, and an organic light emitting layer disposed therebetween. The organic light emitting diode (OLED) may be referred to as one light emitting cell (light emitting unit). All organic light emitting diode structures that are generally used can be applied to organic light emitting diodes (OLEDs).

The driving transistor DRT includes a gate terminal (hereinafter, a driving gate terminal) DG1, a first terminal (hereinafter, a first driving terminal) DE1, and a second terminal (hereinafter, a second driving terminal) DE2. can do. The first power supply voltage ELVDD may be applied to the first driving terminal DE1, and the second driving terminal DE2 may be electrically connected to the organic light emitting diode OLED. The second driving terminal DE2 may be electrically connected to the anode side of the organic light emitting diode OLED. The first driving terminal DE1 may be a source terminal (electrode), and the second driving terminal DE2 may be a drain terminal (electrode).

The pixel circuit may include first to sixth switching transistors T1 to T6. The first switching transistor T1 may be connected to the driving transistor DRT. The first switching transistor T1 is connected to the first gate terminal G1 to which the first scan signal SCAN1 is applied, the 1-1 terminal E11 to which the reference voltage VREF is applied, and the driving gate terminal DG1. It may include electrically connected first and second terminals E12. The 1-1 terminal E11 may be a source terminal, and the 1-2 terminal E12 may be a drain terminal.

The second switching transistor T2 includes a second gate terminal G2 to which the second scan signal SCAN2 is applied, a 2-1 terminal E21 to which the data voltage VDATA is applied, and a 1-2 terminal E12 to which the data voltage VDATA is applied. ) may include a 2-2 terminal E22 electrically connected to the terminal. The 2-1 terminal E21 may be a source terminal, and the 2-2 terminal E22 may be a drain terminal.

The third switching transistor T3 is a third gate terminal G3 to which the third scan signal SCAN3 is applied and electrically connected to the 1-2 terminals E12 and 2-2 terminals E22. A 3-2 terminal E32 electrically connected to the first terminal E31 and the second driving terminal DE2 may be included. The 3-1 terminal E31 may be a source terminal, and the 3-2 terminal E32 may be a drain terminal or vice versa.

The fourth switching transistor T4 is a 4-1 electrically connected to the fourth gate terminal G4 to which the fourth scan signal SCAN4 is applied, the second driving terminal DE2, and the 3-2 terminal E32. A terminal E41 and a 4-2 terminal E42 spaced apart from the 4-1 terminal E41 may be included. The 4-2 terminal E42 may be grounded. The 4-1 terminal E41 may be a source terminal, and the 4-2 terminal E42 may be a drain terminal.

The fifth switching transistor T5 may be connected between the driving transistor DRT and the organic light emitting diode OLED. The fifth switching transistor T5 is connected to the fifth gate terminal G5 to which the emission control signal EM is applied, the 5-1 terminal E51 connected to the driving transistor DRT, and the organic light emitting diode OLED. 5-2 terminal (E52) may be included. The 5-1 terminal E51 may be connected to the second driving terminal DE2, and the 5-2 terminal E52 may be connected to the anode of the organic light emitting diode OLED. The 5-1 terminal E51 may be a source terminal, and the 5-2 terminal E52 may be a drain terminal.

)가 인가되는 제 6 게이트 단자(G6)와 상기 전원부에 연결된 제 6-1 단자(E61) 및 제 1 구동 단자(DE1)에 연결된 제 6-2 단자(E62)를 포함할 수 있다. 여기서, 상기 인버스 신호(

)는 제 4 스캔 신호(SCAN4)에 반대되는 신호일 수 있다. 만약 제 4 스캔 신호(SCAN4)가 하이(high) 신호인 경우, 상기 인버스 신호(

)는 로우(low) 신호일 수 있고, 제 4 스캔 신호(SCAN4)가 로우(low) 신호인 경우, 상기 인버스 신호(

)는 하이(high) 신호일 수 있다. 여기서, 만일 상기 하이(high) 신호가 해당 트랜지스터를 온(ON)시키는 신호인 경우, 상기 로우(low) 신호는 해당 트랜지스터를 온(ON)시키지 않는 신호일 수 있다. 제 6-1 단자(E61)는 소스 단자일 수 있고, 제 6-2 단자(E62)는 드레인 단자일 수 있다. The sixth switching transistor T6 may be connected between the power supply unit generating the first power voltage ELVDD and the driving transistor DRT. The sixth switching transistor T6 is a fourth scan signal SCAN4 to an inverse signal of the fourth scan signal SCAN4 (ie,

) may be applied to the sixth gate terminal G6, a 6-1 terminal E61 connected to the power supply, and a 6-2 terminal E62 connected to the first driving terminal DE1. Here, the inverse signal (

) may be a signal opposite to the fourth scan signal SCAN4. If the fourth scan signal SCAN4 is a high signal, the inverse signal (

) may be a low signal, and when the fourth scan signal SCAN4 is a low signal, the inverse signal (

) may be a high signal. Here, if the high signal is a signal that turns on a corresponding transistor, the low signal may be a signal that does not turn on a corresponding transistor. The 6-1 terminal E61 may be a source terminal, and the 6-2 terminal E62 may be a drain terminal.

In this embodiment, when the fourth scan signal SCAN4 is a high signal, the fourth switching transistor T4 may be turned on and the sixth switching transistor T6 may be turned off. can be Meanwhile, when the fourth scan signal SCAN4 is a low signal, the fourth switching transistor T4 may be in an off state and the sixth switching transistor T6 may be in an on state. can The fourth switching transistor T4 and the sixth switching transistor T6 may be turned on or turned off opposite to each other. In other words, the on/off state of the fourth switching transistor T4 may be opposite to that of the sixth switching transistor T6.

If the fourth scan signal SCAN4 is applied to the sixth gate terminal G6, the fourth switching transistor T4 is turned on by the fourth scan signal SCAN4 having the first condition. , the sixth switching transistor T6 may be turned off by the fourth scan signal SCAN4 having the first condition. In addition, when the fourth switching transistor T4 is turned off by the fourth scan signal SCAN4 having the second condition, the sixth switching transistor T4 is turned off by the fourth scan signal SCAN4 having the second condition. Transistor T6 may be turned on.

The pixel circuit according to the present embodiment may further include first and second capacitors C1 and C2. The first capacitor C1 may be connected between the first switching transistor T1 and the third switching transistor T3. The first capacitor C1 may include a 1-1 electrode e11 connected to the 1-2 terminal E12 and a 1-2 electrode e12 connected to the 3-1 terminal E31. A predetermined first dielectric layer may be disposed between the 1-1 electrode e11 and the 1-2 electrode e12.

The second capacitor C2 may be connected between the second switching transistor T2 and the fourth switching transistor T4. The second capacitor C2 includes the 2-1 electrode e21 connected to the 2-2 terminal E22 and the 3-1 terminal E31, the 3-2 terminal E32 and the 4-1 terminal ( A 2-2 electrode e22 connected to E41) may be included. A predetermined second dielectric layer may be disposed between the 2-1 electrode e21 and the 2-2 electrode e22.

The pixel circuit may include first to fifth nodes N1 to N5. The arrangement of the first to fifth nodes N1 to N5 and the connection relationship with the other components DRT, T1 to T5, C1, and C2 may be the same as those described in FIG. 1 . In addition, the arrangement of the elements DRT, T1 to T6, C1, and C2 of the pixel circuit and the nodes N1 to N5 and the connection relationship between them may be as shown in FIG. 10 .

Meanwhile, the second power supply voltage ELVSS may be applied to an end (ie, cathode) of the organic light emitting diode OLED. The first power supply voltage ELVDD may be a high potential voltage (high potential driving voltage or high potential pixel voltage), and the second power supply voltage ELVSS may be a low potential voltage (low potential driving voltage or low potential pixel voltage). there is. For example, the second power supply voltage ELVSS may be a ground voltage.

The pixel circuit according to the embodiment shown in FIG. 10 may be a circuit for constructing a 'sequential emission type display device'. That is, the pixel circuit of FIG. 10 may be a circuit for configuring a sequential emission type display device in which a plurality of pixel areas sequentially emit light. Also, at least one of the first to sixth switching transistors T1 to T6 and the driving transistor DRT may be, for example, an oxide thin film transistor. All of the first to sixth switching transistors T1 to T6 and the driving transistor DRT may be oxide thin film transistors. In this case, it can be said that the pixel circuit has a circuit configuration based on an oxide thin film transistor. However, in some cases, at least one of the first to sixth switching transistors T1 to T6 and the driving transistor DRT may be a transistor other than an oxide thin film transistor. The pixel circuit according to the present exemplary embodiment may be configured to perform threshold voltage compensation and mobility compensation of the driving transistor DRT.

11 is a diagram (driving waveform diagram) for explaining an operating method (driving method) of a pixel circuit according to another embodiment of the present invention. This embodiment is an operation method of the pixel circuit described in FIG. 10 .

Referring to FIG. 11 , the operation method of the pixel circuit according to the present embodiment includes an initialization step (S21), a threshold voltage compensation step (S22), a data input step (S23), a stabilization step (S24), and a mobility compensation step (S25). ), a holding step (S26) and a light emitting step (S27). The threshold voltage compensation step ( S22 ), the data input step ( S23 ), the mobility compensation step ( S25 ), and the light emission step ( S27 ) may be substantially (or alternatively) essential steps. The initialization step (S21), the stabilization step (S24), and the holding step (S26) may be omitted or modifiable steps, depending on circumstances.

Hereinafter, with reference to FIGS. 12A to 18B , the aforementioned initialization step (S21), threshold voltage compensation step (S22), data input step (S23), stabilization step (S24), mobility compensation step (S25), holding Each of the step S26 and light emission step S27 will be described in detail.

FIG. 12A is a circuit diagram showing an operating state of a pixel circuit in an initialization step ( S21 ) of FIG. 11 . 12B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the initialization step (S21).

12A and 12B, in the initialization step (S21), the first, third and fourth switching transistors T1, T3 and T4 are turned on, and the second and sixth switching transistors T2 and T6 are turned on. ) can be turned off to reset the first and second capacitors C1 and C2. Signals SCAN1, SCAN3, and SCAN4 may be applied as high and the signal SCAN2 may be applied as low, and as a result, the first, third, and fourth switching transistors T1, T3, and T4 are turned on (ON). ) state, and the second and sixth switching transistors T2 and T6 may be turned off. The upper voltage of the first capacitor C1 may be V _REF (ie, VREF: reference voltage), and the lower voltage of the first capacitor C1 (ie, the voltage at the left end of C2) and the second capacitor C2 All of the voltages at the right end of may be initialized to OV [ie, GND (ground)]. Accordingly, the voltage stored in the first capacitor C1 may be V _REF , and the voltage stored in the second capacitor C2 may be 0 V. At this time, the fifth switching transistor T5 may be in an off state.

FIG. 13A is a circuit diagram showing an operating state of a pixel circuit in the threshold voltage compensating step ( S22 ) of FIG. 11 . 13B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the threshold voltage compensating step (S22).

13A and 13B, in the threshold voltage compensating step (S22), the first, third, and sixth switching transistors T1, T3, and T6 are turned on, and the second and fourth switching transistors T2 , T4 may be turned off so that the voltage V _{TH_DRT} corresponding to the threshold voltage of the driving transistor DRT may be stored in the first capacitor C1. Signals SCAN1 and SCAN3 may be applied high, and signals SCAN2 and SCAN4 may be applied low, and as a result, the first, third, and sixth switching transistors T1, T3, and T6 are turned on (ON). ) state, and the second and fourth switching transistors T2 and T4 may be turned off. The upper voltage of the first capacitor C1 may be maintained at VREF, and the lower voltage of the first capacitor C1 may be charged up to V _REF - V _{TH_DRT} . Here, V _{TH_DRT} may be a threshold voltage of the driving transistor DRT. Accordingly, the voltage V _{TH_DRT} corresponding to the threshold voltage of the driving transistor DRT may be stored in the first capacitor C1.

FIG. 14A is a circuit diagram showing an operating state of a pixel circuit in the data input step ( S23 ) of FIG. 11 . 14B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the data input step (S23).

14A and 14B, in the data input step (S23), the first, third and sixth switching transistors T1, T3 and T6 are turned off, and the second and fourth switching transistors T2 and T6 are turned off. By turning on T4 and applying the data voltage VDATA to the second switching transistor T2, the voltage corresponding to the data voltage VDATA to the second capacitor C2 (ie, marked as V _DATA voltage) can be stored. Signals SCAN2 and SCAN4 may be applied as high and signals SCAN1 and SCAN3 may be applied as low, and as a result, the second and fourth switching transistors T2 and T4 are turned on, The first, third, and sixth switching transistors T1, T3, and T6 may be turned off. V _DATA may be applied to the left side of the second capacitor C2, and 0 V (ie, GND) may be applied to the right side of the second capacitor C2.

A display device including the pixel circuit of this embodiment may be a sequential emission type display device. The sequential emission type display device may include a plurality of data lines (vertical lines), and data input may be performed on only one data line among the plurality of data lines in the data input step S23.

FIG. 15A is a circuit diagram showing an operating state of a pixel circuit in the stabilization step ( S24 ) of FIG. 11 . 15B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the stabilization step (S24).

15A and 15B, by turning off the first to fourth switching transistors T1 to T4 in the stabilization step S24, the voltages stored in the first and second capacitors C1 and C2, respectively, are reduced. can be stabilized. In this step (S24), the SCAN1, SCAN2, SCAN3, and SCAN4 signals may all be applied as low.

FIG. 16A is a circuit diagram showing an operating state of a pixel circuit in the mobility compensation step ( S25 ) of FIG. 11 . 16B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the mobility compensation step (S25).

16A and 16B, in a state in which the second to fourth switching transistors T2 to T4 are turned off and the sixth switching transistor T6 is turned on in the mobility compensation step (S25), By turning on the first switching transistor T1, the sum of the voltages stored in the first and second capacitors C1 and C2 is a compensation voltage proportional to the mobility μ _{n_DRT} of the driving transistor DRT [that is, , ΔV (μ _{n_DRT} , t, V _DATA )]. Signals SCAN1, SCAN2, SCAN3, and SCAN4 may all be applied as low, and only the signal SCAN1 may be applied as high. When the SCAN1 signal is applied as high, a current proportional to V _DATA + V _{TH_DRT} , which is the voltage between the gate and source of the driving transistor DRT, and the mobility flows, and the first and second capacitors C1 and C2 The sum of the stored voltages may decrease by ΔV (μ _{n_DRT} , t, V _DATA ). Since ΔV (μ _{n_DRT} , t, V _DATA ) in this step is a value affected not only by mobility but also by V _DATA , the characteristic that mobility varies according to voltage can be reflected in the mobility compensation process. ΔV (μ _{n_DRT} , t, V _DATA ) may increase as the mobility μ _{n_DRT} of the driving transistor DRT increases, as the mobility compensation time t increases, and as V _DATA increases.

FIG. 17A is a circuit diagram showing an operating state of the pixel circuit in the holding step ( S26 ) of FIG. 11 . 17B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the holding step (S26).

17A and 17B, in the holding step (S26), the first to fifth switching transistors T1 to T5 are turned off and the sixth switching transistor T6 is kept turned on (ON) That is, you can hold). In order to adjust the emission time (ie, emission ratio), a time interval may be provided until the EM signal (emission control signal) is applied as high.

FIG. 18A is a circuit diagram showing an operating state of a pixel circuit in the light emitting step ( S27 ) of FIG. 11 . 18B is a waveform diagram emphasizing the shapes of signals applied to the pixel circuit in the light emitting step (S27).

Referring to FIGS. 18A and 18B , the organic light emitting diode (OLED) may emit light in the light emitting step ( S27 ). The OLED may emit light using the gate-source voltage of the driving transistor DRT stored through the previous steps. At this time, the current flowing through the organic light emitting diode (OLED), that is, I _OLED may be defined as in Equation 1 above.

As the mobility μ _{n_DRT} of the driving transistor DRT increases, the voltage to be corrected (reduced) increases, and thus the final driving voltage may decrease. Accordingly, a current error due to a difference in mobility may be corrected.

According to the embodiments of the present invention, it is possible to provide a pixel circuit that can easily perform mobility compensation as well as threshold voltage compensation of a driving transistor, and also easily perform a data input operation and an operating method thereof. there is. Using the pixel circuit and its operating method according to the embodiments, it is possible to effectively and accurately compensate for the deviation/dispersion of electrical characteristics (threshold voltage, mobility) of the driving transistors, and to improve a problem such as luminance non-uniformity to achieve a uniform picture quality. can be implemented. In particular, according to an embodiment of the present invention, it is expected that much more uniform picture quality can be implemented than when only the threshold voltage distribution is compensated.

By applying the pixel circuit and its operating method (driving method) according to embodiments of the present invention, an organic light emitting display device having excellent image quality uniformity and high reliability and an operating method (driving method) thereof can be implemented. The organic light emitting display device described above may be referred to as a display device based on an active matrix organic light emitting device. At least some of the effects obtained from the embodiments of the present invention can be further enhanced when at least one of the switching transistors and the driving transistor is an oxide thin film transistor, but in some cases, a transistor other than the oxide thin film transistor may be used. there is.

19 to 22 are graphs showing results obtained by verifying driving characteristics of the pixel circuit having the configuration of FIG. 1 using simulation program with integrated circuit emphasis (SPICE).

19 shows a change in compensation current according to a change in threshold voltage, FIG. 20 shows a change in compensation current according to a change in mobility, and FIG. 21 shows the error rate (%) according to a change in threshold voltage. 22 shows the change in error rate (%) according to the change in mobility.

23 to 26 are graphs showing results of verifying driving characteristics of the pixel circuit having the configuration of FIG. 10 using SPICE simulation.

23 shows a change in compensation current according to a change in threshold voltage, FIG. 24 shows a change in compensation current according to a change in mobility, and FIG. 25 shows the error rate (%) according to a change in threshold voltage. 26 shows the change in error rate (%) according to the change in mobility.

Referring to FIGS. 19 to 22 and 23 to 26 , it can be confirmed that excellent driving characteristics can be implemented by threshold voltage compensation and mobility compensation, etc., when the pixel circuit having the configuration of FIG. 1 or 10 is used. .

In this specification, preferred embodiments of the present invention have been disclosed, and although specific terms have been used, they are only used in a general sense to easily explain the technical details of the present invention and help understanding of the present invention, and do not limit the scope of the present invention. It is not meant to be limiting. It is obvious to those skilled in the art that other modifications based on the technical idea of the present invention can be implemented in addition to the embodiments disclosed herein. A pixel circuit according to the embodiments described with reference to FIGS. 1 to 26 , an organic light emitting display device including the pixel circuit, and an operating method thereof, according to the embodiments described with reference to FIGS. 1 to 26 , to those skilled in the art It will be appreciated that various substitutions, changes, and modifications may be made within the range that does not deviate from this. Therefore, the scope of the invention should not be determined by the described embodiments, but by the technical idea described in the claims.

* Description of symbols for main parts of drawings *
C1: 1st capacitor C2: 2nd capacitor
DE1: 1st drive terminal DE2: 2nd drive terminal
DG1: driving gate terminal DRT: driving transistor
e11 to e22: Electrode E11 to E62: Terminal
EM: light emission control signal ELVDD: first power supply voltage
ELVSS: Second power supply voltage G1 to G6: Gate terminal
N1∼N5: node OLED: organic light emitting device
SCAN1: 1st scan signal SCAN2: 2nd scan signal
SCAN3: 3rd scan signal SCAN4: 4th scan signal
T1: 1st switching transistor T2: 2nd switching transistor
T3: 3rd switching transistor T4: 4th switching transistor
T5: 5th switching transistor T6: 6th switching transistor
VDATA: data signal VREF: reference signal

Claims (20)

a light emitting diode-based light emitting device;
a driving transistor for controlling driving of the light emitting element, having a driving gate terminal, a first driving terminal to which a first power supply voltage is applied, and a second driving terminal electrically connected to the light emitting element;
A first switching transistor connected to the driving transistor and having a first gate terminal to which a first scan signal is applied, a 1-1 terminal to which a reference voltage is applied, and a 1-2 terminal electrically connected to the driving gate terminal ;
a second switching transistor having a second gate terminal to which a second scan signal is applied, a 2-1 terminal to which a data voltage is applied, and a 2-2 terminal electrically connected to the 1-2 terminal;
A third gate terminal to which a third scan signal is applied, a 3-1 terminal electrically connected to the 1-2 terminal and the 2-2 terminal, and a 3-2 terminal electrically connected to the second driving terminal a third switching transistor having;
A fourth gate terminal to which the second scan signal is applied, a 4-1 terminal electrically connected to the second driving terminal and the 3-2 terminal, and a 4-2 disposed spaced apart from the 4-1 terminal. a fourth switching transistor having a terminal;
A fifth switching transistor connected between the driving transistor and the light emitting element and having a fifth gate terminal to which a light emitting control signal is applied, a 5-1 terminal connected to the driving transistor, and a 5-2 terminal connected to the light emitting element ;
a first capacitor connected between the first switching transistor and the third switching transistor and having a 1-1 electrode connected to the 1-2 terminal and a 1-2 electrode connected to the 3-1 terminal; and
a 2-1 electrode connected to the 2-2 terminal and the 3-1 terminal, the 3-2 terminal and the 4-1 terminal connected between the second switching transistor and the fourth switching transistor; A pixel circuit including a second capacitor having a 2-2 electrode connected to . According to claim 1,
At least one of the first to fifth switching transistors and the driving transistor is an oxide thin film transistor. According to claim 1,
The pixel circuit is configured to perform threshold voltage compensation and mobility compensation of the driving transistor. According to claim 1,
The pixel circuit is a circuit for constituting a simultaneous emission type display device. a light emitting device based on a light emitting diode;
a driving transistor for controlling driving of the light emitting element, having a driving gate terminal, a first driving terminal to which a first power supply voltage is applied, and a second driving terminal electrically connected to the light emitting element;
a first switching transistor connected to the driving transistor and having a first gate terminal to which a first scan signal is applied, a 1-1 terminal to which a reference voltage is applied, and a 1-2 terminal electrically connected to the driving gate terminal;
a second switching transistor having a second gate terminal to which a second scan signal is applied, a 2-1 terminal to which a data voltage is applied, and a 2-2 terminal electrically connected to the 1-2 terminal;
A third gate terminal to which a third scan signal is applied, a 3-1 terminal electrically connected to the 1-2 terminal and the 2-2 terminal, and a 3-2 terminal electrically connected to the second driving terminal a third switching transistor having;
A 4-1 terminal electrically connected to a fourth gate terminal to which a fourth scan signal is applied, the second driving terminal, and the 3-2 terminal, and a 4-2 terminal spaced apart from the 4-1 terminal A fourth switching transistor having a;
A fifth switching transistor connected between the driving transistor and the light emitting element and having a fifth gate terminal to which a light emitting control signal is applied, a 5-1 terminal connected to the driving transistor, and a 5-2 terminal connected to the light emitting element ;
A sixth gate terminal connected between a power supply unit generating the first power supply voltage and the driving transistor, to which the fourth scan signal or an inverse signal of the fourth scan signal is applied, and a sixth-connected power supply unit a sixth switching transistor having a first terminal and a 6-2 terminal connected to the first driving terminal;
a first capacitor connected between the first switching transistor and the third switching transistor and having a 1-1 electrode connected to the 1-2 terminal and a 1-2 electrode connected to the 3-1 terminal; and
a 2-1 electrode connected to the 2-2 terminal and the 3-1 terminal, the 3-2 terminal and the 4-1 terminal connected between the second switching transistor and the fourth switching transistor; A pixel circuit including a second capacitor having a 2-2 electrode connected to . According to claim 5,
At least one of the first to sixth switching transistors and the driving transistor is an oxide thin film transistor. According to claim 5,
When the fourth switching transistor is in an on state, the sixth switching transistor is in an off state,
When the fourth switching transistor is in an off state, the sixth switching transistor is in an on state. According to claim 5,
The pixel circuit is configured to perform threshold voltage compensation and mobility compensation of the driving transistor. According to claim 5,
The pixel circuit is a circuit for constituting a sequential emission type display device. An organic light emitting display device comprising the pixel circuit according to any one of claims 1 to 9. As a method of operating the pixel circuit according to claim 1,
A threshold voltage for storing a voltage corresponding to the threshold voltage of the driving transistor in the first capacitor by turning on the first and third switching transistors and turning off the second and fourth switching transistors. compensation phase;
The data voltage is stored in the second capacitor by turning off the first and third switching transistors, turning on the second and fourth switching transistors, and applying the data voltage to the second switching transistor. a data input step of storing a voltage corresponding to the voltage;
By turning on the first switching transistor in a state where the second to fourth switching transistors are turned off, the sum of the voltages stored in the first and second capacitors is proportional to the mobility of the driving transistor. A mobility compensation step of compensating with a compensation voltage; and
A method of operating a pixel circuit comprising a light emitting step of emitting light from the light emitting element. According to claim 11,
and an initialization step of resetting the first and second capacitors by turning on the first to fourth switching transistors before the threshold voltage compensating step. According to claim 11,
The pixel circuit may further include a stabilization step of stabilizing voltages stored in the first and second capacitors, respectively, by turning off the first to fourth switching transistors between the data input step and the mobility compensating step. how it works. According to claim 11,
The method of operating a pixel circuit further comprising a holding step of maintaining a state in which the first to fifth switching transistors are turned off between the mobility compensation step and the light emitting step. According to claim 11,
A plurality of data lines to which signals corresponding to the data voltages are applied are provided, and the data input step is performed for the plurality of data lines. As a method of operating the pixel circuit according to claim 5,
A voltage corresponding to the threshold voltage of the driving transistor is stored in the first capacitor by turning on the first, third and sixth switching transistors and turning off the second and fourth switching transistors. a threshold voltage compensation step;
By turning off the first, third and sixth switching transistors, turning on the second and fourth switching transistors, and applying the data voltage to the second switching transistor, the second capacitor a data input step of storing a voltage corresponding to the data voltage to;
By turning on the first switching transistor in a state where the second to fourth switching transistors are turned off and the sixth switching transistor is turned on, the voltage stored in the first and second capacitors is reduced. a mobility compensation step of compensating the sum with a compensation voltage proportional to the mobility of the driving transistor; and
A method of operating a pixel circuit comprising a light emitting step of emitting light from the light emitting element. 17. The method of claim 16,
Before the threshold voltage compensating step, by turning on the first, third and fourth switching transistors and turning off the second and sixth switching transistors, the first and second capacitors are initialized ( A method of operating a pixel circuit further comprising an initialization step of resetting. 17. The method of claim 16,
The pixel circuit may further include a stabilization step of stabilizing voltages stored in the first and second capacitors, respectively, by turning off the first to fourth switching transistors between the data input step and the mobility compensating step. how it works. 17. The method of claim 16,
Between the mobility compensation step and the light emitting step, a holding step of turning off the first to fifth switching transistors and maintaining the sixth switching transistor in an on state Further comprising How the pixel circuit works. A method of operating an organic light emitting display device comprising the method of operating a pixel circuit according to any one of claims 11 to 19.

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