Pixel circuit

Abstract

A pixel circuit is provided, the pixel circuit comprising: an organic light emitting element; a switching transistor; a storage capacitor storing a data signal applied via a data line; a driving transistor allowing a driving current corresponding to the data signal to flow into the organic light emitting element; an emission control transistor electrically connected in series to the organic light emitting element and the driving transistor; and a synchronous transistor electrically connected to a bottom metal electrode of the driving transistor. The synchronous transistor comprises: a first synchronous transistor electrically connected to a first one selected from a source electrode of the driving transistor, a gate electrode of the driving transistor, a high power supply voltage, and a low power supply voltage; and a second synchronous transistor electrically connected to a second one selected from a source electrode of the driving transistor, a gate electrode of the driving transistor, a high power supply voltage, and a low power supply voltage.

Description

Technical Field

[0001] Exemplary embodiments of the invention generally relate to an organic light emitting display device, and more particularly to a pixel circuit including an organic light emitting element (eg, an organic light emitting diode), a switching transistor, a storage capacitor, an emission control transistor, a driving transistor, and the like. Background Art

[0002] Typically, a pixel circuit included in an organic light-emitting display device includes an organic light-emitting element, a switching transistor, a storage capacitor, an emission control transistor, a driving transistor, etc. Recently, a "reverse bias" technology (also called a "synchronous" technology) has been proposed. The "reverse bias" technology forms a bottom metal layer (BML) under a thin film transistor (e.g., an oxide thin film transistor, etc.) included in the pixel circuit, wherein the bottom metal layer can be referred to as a bottom metal electrode of the thin film transistor, and the "reverse bias" technology shifts (or moves) the threshold voltage of the thin film transistor in a positive or negative direction by applying a reverse bias voltage to the bottom metal electrode of the thin film transistor when the pixel circuit is driven. However, because the conventional reverse bias technology determines (or fixes) the purpose of applying the reverse bias voltage to the bottom metal electrode of the thin film transistor in the design stage of the pixel circuit (for example, applying the reverse bias voltage to the bottom metal electrode of the driving transistor to reduce (or improve) the instantaneous afterimage of the organic light-emitting display device; applying the reverse bias voltage to the bottom metal electrode of the driving transistor to increase (or improve) the emission brightness of the organic light-emitting display device, etc.), the direction of the threshold voltage shift of the thin film transistor (for example, the driving transistor) can only be determined as one direction in the design stage of the pixel circuit. Therefore, the conventional reverse bias technology cannot selectively shift the threshold voltage of the driving transistor in the positive direction or in the negative direction according to the operation stage (for example, initialization stage, threshold voltage compensation stage, data writing stage, light-emitting stage, etc.) and / or operation conditions of the organic light-emitting display device.

[0003] The above information disclosed in this Background section is only for understanding the background of the inventive concept and therefore it may contain information that does not constitute the prior art. Summary of the invention

[0004] Exemplary embodiments of the invention provide a pixel circuit having a structure in which a threshold voltage of a driving transistor can be selectively shifted in a positive direction or in a negative direction according to an operation phase and / or an operation condition of an organic light emitting display device.

[0005] Additional features of the inventive concepts will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the inventive concepts.

[0006] An exemplary embodiment of the invention provides a pixel circuit, the pixel circuit comprising: an organic light emitting element; a switching transistor configured to be turned on or off in response to a scan signal; a storage capacitor configured to store a data signal applied via a data line when the switching transistor is turned on in response to the scan signal; a driving transistor configured to allow a driving current corresponding to the data signal stored in the storage capacitor to flow into the organic light emitting element; an emission control transistor electrically connected in series to the organic light emitting element and the driving transistor between a high power supply voltage and a low power supply voltage, and configured to be turned on or off in response to an emission control signal; and a plurality of synchronous transistors electrically connected to a bottom metal electrode of the driving transistor. The synchronous transistor may include: a first synchronous transistor electrically connected to a first one selected from a source electrode of the driving transistor, a gate electrode of the driving transistor, a high power supply voltage, and a low power supply voltage; and a second synchronous transistor electrically connected to a second one selected from a source electrode of the driving transistor, a gate electrode of the driving transistor, a high power supply voltage, and a low power supply voltage, and the second one is different from the first one.

[0007] When the first synchronous transistor is turned on, the second synchronous transistor may be turned off. In addition, when the second synchronous transistor is turned on, the first synchronous transistor may be turned off.

[0008] Another exemplary embodiment of the invention provides a pixel circuit, which includes: an organic light emitting element; a switching transistor configured to be turned on or off in response to a scanning signal; a storage capacitor configured to store a data signal applied via a data line when the switching transistor is turned on in response to the scanning signal; a driving transistor configured to allow a driving current corresponding to the data signal stored in the storage capacitor to flow into the organic light emitting element; an emission control transistor electrically connected in series to the organic light emitting element and the driving transistor between a high power supply voltage and a low power supply voltage, and configured to be turned on or off in response to an emission control signal; a source synchronous transistor electrically connected between a source electrode of the driving transistor and a bottom metal electrode of the driving transistor, and configured to be turned on or off in response to a source synchronous control signal; and a gate synchronous transistor electrically connected between a gate electrode of the driving transistor and a bottom metal electrode of the driving transistor, and configured to be turned on or off in response to a gate synchronous control signal.

[0009] The driving transistor may be a p-channel metal oxide semiconductor transistor. In addition, when the source synchronous transistor is turned on in response to the source synchronous control signal, the threshold voltage of the driving transistor may be shifted in a negative direction.

[0010] The source synchronous control signal may be activated during a first period when the driving current flowing into the organic light emitting element needs to be reduced. In addition, the source synchronous transistor may be turned on during the first period to allow the source voltage of the source electrode of the driving transistor to be applied to the bottom metal electrode of the driving transistor.

[0011] The driving transistor may be a p-channel metal oxide semiconductor transistor. In addition, when the gate synchronous transistor is turned on in response to the gate synchronous control signal, the threshold voltage of the driving transistor may be shifted in a positive direction.

[0012] The gate synchronization control signal may be activated during the second period when the driving current flowing into the organic light emitting element needs to be increased. In addition, the gate synchronization transistor may be turned on during the second period to allow the gate voltage of the gate electrode of the driving transistor to be applied to the bottom metal electrode of the driving transistor.

[0013] The pixel circuit may further include: a constant voltage synchronous transistor electrically connected between the bottom metal electrode of the driving transistor and the constant voltage supply line and configured to be turned on or off in response to a constant voltage synchronous control signal.

[0014] The driving transistor may be a p-channel metal oxide semiconductor transistor. In addition, the constant voltage supplied via the constant voltage supply line may have a positive voltage level. In addition, when the constant voltage synchronous transistor is turned on in response to the constant voltage synchronous control signal, the threshold voltage of the driving transistor may shift in a negative direction.

[0015] The constant voltage can be a high supply voltage.

[0016] The constant voltage synchronous control signal may be activated during the third period when the driving current flowing into the organic light emitting element needs to be reduced. In addition, the constant voltage synchronous transistor may be turned on during the third period to allow a constant voltage to be applied to the bottom metal electrode of the driving transistor.

[0017] The driving transistor may be a p-channel metal oxide semiconductor transistor. In addition, the constant voltage supplied via the constant voltage supply line may have a negative voltage level. In addition, when the constant voltage synchronous transistor is turned on in response to the constant voltage synchronous control signal, the threshold voltage of the driving transistor may shift in the positive direction.

[0018] The constant voltage can be a low supply voltage.

[0019] The constant voltage synchronous control signal may be activated during the fourth period when the driving current flowing into the organic light emitting element needs to be increased. In addition, the constant voltage synchronous transistor may be turned on during the fourth period to allow a constant voltage to be applied to the bottom metal electrode of the driving transistor.

[0020] Another exemplary embodiment of the invention provides a pixel circuit, which includes: an organic light emitting element; a switching transistor configured to be turned on or off in response to a scanning signal; a storage capacitor configured to store a data signal applied via a data line when the switching transistor is turned on in response to the scanning signal; a driving transistor configured to allow a driving current corresponding to the data signal stored in the storage capacitor to flow into the organic light emitting element; an emission control transistor electrically connected in series to the organic light emitting element and the driving transistor between a high power supply voltage and a low power supply voltage, and configured to be turned on or off in response to the emission control signal; a source synchronous transistor electrically connected between a source electrode of the driving transistor and a bottom metal electrode of the driving transistor, and configured to be turned on or off in response to a source synchronous control signal; and a constant voltage synchronous transistor electrically connected between the bottom metal electrode of the driving transistor and a constant voltage supply line, and configured to be turned on or off in response to the constant voltage synchronous control signal.

[0021] The driving transistor may be a p-channel metal oxide semiconductor transistor. In addition, when the source synchronous transistor is turned on in response to the source synchronous control signal, the threshold voltage of the driving transistor may be shifted in a negative direction.

[0022] The driving transistor may be a p-channel metal oxide semiconductor transistor. In addition, when the constant voltage synchronous transistor is turned on in response to the constant voltage synchronous control signal, the threshold voltage of the driving transistor may shift in a positive direction or in a negative direction.

[0023] Another exemplary embodiment of the invention provides a pixel circuit, which includes: an organic light emitting element; a switching transistor configured to be turned on or off in response to a scanning signal; a storage capacitor configured to store a data signal applied via a data line when the switching transistor is turned on in response to the scanning signal; a driving transistor configured to allow a driving current corresponding to the data signal stored in the storage capacitor to flow into the organic light emitting element; an emission control transistor electrically connected in series to the organic light emitting element and the driving transistor between a high power supply voltage and a low power supply voltage, and configured to be turned on or off in response to the emission control signal; a gate synchronization transistor electrically connected between a gate electrode of the driving transistor and a bottom metal electrode of the driving transistor, and configured to be turned on or off in response to a gate synchronization control signal; and a constant voltage synchronization transistor electrically connected between the bottom metal electrode of the driving transistor and a constant voltage supply line, and configured to be turned on or off in response to the constant voltage synchronization control signal.

[0024] The driving transistor may be a p-channel metal oxide semiconductor transistor. In addition, when the gate synchronous transistor is turned on in response to the gate synchronous control signal, the threshold voltage of the driving transistor may be shifted in a positive direction.

[0025] The driving transistor may be a p-channel metal oxide semiconductor transistor. In addition, when the constant voltage synchronous transistor is turned on in response to the constant voltage synchronous control signal, the threshold voltage of the driving transistor may shift in a positive direction or in a negative direction.

[0026] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the inventive concept.

[0028] Figure 1 is a diagram illustrating a pixel circuit according to an exemplary embodiment.

[0029] Figure 2 It is shown Figure 1 FIG. 1 is a diagram of an example of a pixel circuit.

[0030] Figure 3 It is shown that the Figure 1 A cross-sectional view of an example of the structure of a driving transistor in a pixel circuit.

[0031] Figure 4 It is shown Figure 1 FIG. 1 is a diagram of another example of a pixel circuit of FIG.

[0032] Figure 5 It is shown Figure 1 FIG. 1 is a diagram of yet another example of a pixel circuit.

[0033] Figure 6 It is shown Figure 1 FIG. 1 is a diagram of yet another example of a pixel circuit.

[0034] Figure 7 It is shown Figure 1 FIG. 1 is a diagram of yet another example of a pixel circuit.

[0035] Figure 8 It is shown Figure 1 FIG. 1 is a diagram of yet another example of a pixel circuit.

[0036] Fig. 9 It is shown Figure 1 FIG. 1 is a diagram of yet another example of a pixel circuit.

[0037] Fig.10 is a block diagram illustrating an organic light emitting display device according to an exemplary embodiment.

[0038] Fig.11is a block diagram illustrating an electronic device according to an exemplary embodiment.

[0039] Fig.12 It shows that Fig.11 The electronic device is implemented as an example of a smart phone. DETAILED DESCRIPTION

[0040] In the following description, for the purpose of explanation, many specific details are set forth to provide a thorough understanding of the various exemplary embodiments of the invention. "Embodiment" as used herein is a non-limiting example of a device or method using one or more inventive concepts disclosed herein. However, it is apparent that various exemplary embodiments may be practiced without these specific details or in the case of one or more equivalent arrangements. In other cases, in order to avoid making the various exemplary embodiments unnecessarily obscure, known structures and devices are shown in block diagram form. In addition, various exemplary embodiments may be different, but need not be exclusive. For example, without departing from the inventive concept, the specific shape, construction and characteristics of the exemplary embodiment may be used or implemented in another exemplary embodiment.

[0041] Unless otherwise specified, the exemplary embodiments shown will be understood as providing exemplary features of the details of the changes in some ways in which the inventive concept can be implemented in practice. Therefore, unless otherwise specified, the features, components, modules, layers, films, panels, regions and / or aspects, etc. (hereinafter, individually or collectively referred to as "elements") of the various embodiments may be further combined, separated, interchanged and / or rearranged without departing from the inventive concept.

[0042] The use of cross hatching and / or shading in the drawings is generally provided to make the boundaries between adjacent elements clear. Thus, unless otherwise specified, the presence or absence of cross hatching or shading does not convey or indicate any preference or requirement for the specific material, material properties, size, ratio, commonality between the elements shown, and / or any other characteristics, attributes, properties, etc. of the elements. In addition, in the drawings, the size and relative size of the elements may be exaggerated for clarity and / or descriptive purposes. When the exemplary embodiments may be implemented differently, a specific process sequence may be performed differently from the described sequence. For example, two consecutively described processes may be performed substantially simultaneously or in an order opposite to the described sequence. In addition, the same reference numerals represent the same elements.

[0043] When an element or layer is referred to as being "on" another element or layer, "connected to" or "bonded to" another element or layer, the element or layer may be directly on, directly connected to or directly bonded to the other element or layer, or there may be an intermediate element or intermediate layer. However, when an element or layer is referred to as being "directly on" another element or layer, "directly connected to" or "directly bonded to" another element or layer, there is no intermediate element or intermediate layer. For this reason, the term "connection" may refer to a physical connection, an electrical connection and / or a fluid connection with or without an intermediate element. In addition, the D1 axis, the D2 axis and the D3 axis are not limited to three axes such as the x-axis, the y-axis and the z-axis of a rectangular coordinate system, and may be interpreted in a broader sense. For example, the D1 axis, the D2 axis and the D3 axis may be perpendicular to each other, or may represent different directions that are not perpendicular to each other. For the purpose of this disclosure, "at least one of X, Y, and Z" and "at least one selected from the group consisting of X, Y, and Z" may be interpreted as any combination of only X, only Y, only Z, or two or more of X, Y, and Z, such as XYZ, XYY, YZ, and ZZ. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0044] Although the terms "first", "second", etc. may be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another element. Therefore, without departing from the disclosed teachings, the first element discussed below may be referred to as the second element.

[0045] For descriptive purposes, spatially relative terms such as "under," "below," "below," "down," "above," "up," "above," "higher," "side" (e.g., as in "sidewall"), etc., may be used herein to describe the relationship of one element to another element as shown in the accompanying drawings. In addition to the orientation depicted in the accompanying drawings, spatially relative terms are intended to encompass different orientations of the device in use, operation, and / or manufacture. For example, if the device in the accompanying drawings is turned over, an element described as "under" or "beneath" other elements or features would subsequently be positioned "above" the other elements or features. Thus, the exemplary term "under" can encompass both above and below orientations. In addition, the device may be otherwise positioned (e.g., rotated 90 degrees or at other orientations), and as such, the spatially relative descriptors used herein are interpreted accordingly.

[0046] The terms used herein are for the purpose of describing specific embodiments, and are not intended to be limited. As used herein, unless the context clearly indicates otherwise, the singular "one (kind / person)" and "said (the)" are also intended to include plural forms. In addition, when the terms "include" and / or "comprise" are used in this specification, it is explained that there are features, integral bodies, steps, operations, elements, components and / or their groups of elaboration, but one or more other features, integral bodies, steps, operations, elements, components and / or their groups are not excluded from existence or addition. It is also noted that, as used herein, the terms "substantially", "approximately" and other similar terms are used as approximate terms and are not used as terms of degree, so, are used to explain the inherent deviation of measured values, calculated values ​​and / or provided values ​​that will be recognized by those of ordinary skill in the art.

[0047] Various exemplary embodiments are described herein with reference to cross-sectional views and / or exploded views as schematic diagrams of idealized exemplary embodiments and / or intermediate structures. As such, variations in the shapes of the diagrams, such as those caused by manufacturing techniques and / or tolerances, are expected. Therefore, the exemplary embodiments disclosed herein should not necessarily be interpreted as being limited to the shapes of the specifically illustrated regions, but will include deviations in shapes caused by, for example, manufacturing. In this way, the regions shown in the drawings may be schematic in nature, and the shapes of these regions may not reflect the actual shapes of the regions of the device, and as such, no limitation is necessarily intended.

[0048] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those of ordinary skill in the art to which this disclosure is a part. Unless explicitly defined as such herein, terms (such as those defined in general dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and should not be interpreted in an ideal or overly formal sense.

[0049] Figure 1 is a diagram illustrating a pixel circuit according to an exemplary embodiment.

[0050] Reference Figure 1 , a pixel circuit 100 included in an organic light emitting display device may include a main circuit 120 and a sub-circuit 140 .

[0051] The main circuit 120 may receive the data signal DS in response to the scan signal SS, and may output light having a brightness corresponding to the data signal DS in response to the emission control signal ES. In an exemplary embodiment, the main circuit 120 may include an organic light emitting element, a switching transistor, a storage capacitor, a driving transistor, and an emission control transistor. Each of the switching transistor, the driving transistor, and the emission control transistor included in the main circuit 120 may be a p-channel metal oxide semiconductor (PMOS) transistor or an n-channel metal oxide semiconductor (NMOS) transistor. In some exemplary embodiments, each of the switching transistor, the driving transistor, and the emission control transistor included in the main circuit 120 may be implemented by an oxide thin film transistor. Because only the necessary components for the operation of the main circuit 120 (i.e., the organic light emitting element, the switching transistor, the storage capacitor, the driving transistor, and the emission control transistor) are mentioned above, it should be understood that the main circuit 120 may also include other components in addition to the components mentioned above. The organic light emitting element may be an organic light emitting diode. The switching transistor may be turned on or off in response to the scan signal SS. The storage capacitor may store the data signal DS applied via the data line when the switching transistor is turned on in response to the scan signal SS. The driving transistor may allow a driving current corresponding to a data signal DS stored in a storage capacitor to flow into the organic light emitting element. The emission control transistor may be electrically connected in series to the organic light emitting element and the driving transistor between a high power supply voltage ELVDD and a low power supply voltage ELVSS. The emission control transistor may be turned on or off in response to an emission control signal ES. Therefore, the pixel circuit 100 may control the organic light emitting element to emit light during an emission period in which the emission control transistor is turned on, and may control the organic light emitting element not to emit light during a non-emission period in which the emission control transistor is turned off. That is, the pixel circuit 100 may prepare for emission of the organic light emitting element during the non-emission period. The organic light emitting element may emit light having a brightness corresponding to the driving current.

[0052] The subcircuit 140 may be electrically connected to the main circuit 120. Specifically, the subcircuit 140 may receive a synchronization control signal CTLS, and may selectively shift the threshold voltage of the driving transistor based on the synchronization control signal CTLS. For example, the subcircuit 140 may shift the threshold voltage of the driving transistor in a first direction so as to reduce (or improve) the instantaneous afterimage of the organic light-emitting display device; the subcircuit 140 may shift the threshold voltage of the driving transistor in a second direction opposite to the first direction so as to increase (or improve) the emission brightness of the organic light-emitting display device; and the subcircuit 140 may not shift the threshold voltage of the driving transistor. In other words, the subcircuit 140 may selectively shift the threshold voltage of the driving transistor according to the operating stage and / or operating conditions of the organic light-emitting display device. To this end, the sub-circuit 140 may include at least two selected from a source synchronous transistor, a gate synchronous transistor, and a constant voltage synchronous transistor. The source synchronous transistor is electrically connected between the source electrode of the driving transistor and the bottom metal electrode of the driving transistor and is turned on or off in response to a source synchronous control signal. The gate synchronous transistor is electrically connected between the gate electrode of the driving transistor and the bottom metal electrode of the driving transistor and is turned on or off in response to a gate synchronous control signal. The constant voltage synchronous transistor is electrically connected between the bottom metal electrode of the driving transistor and a constant voltage supply line and is turned on or off in response to the constant voltage synchronous control signal. In an exemplary embodiment, the sub-circuit 140 may include a source synchronous transistor and a gate synchronous transistor. The following will refer to Figure 2 and Figure 3 In another exemplary embodiment, the sub-circuit 140 may include a source synchronous transistor, a gate synchronous transistor, and a constant voltage synchronous transistor. Figure 4 and Figure 5 In another exemplary embodiment, the sub-circuit 140 may include a source synchronous transistor and a constant voltage synchronous transistor. Figure 6 and Figure 7 In another exemplary embodiment, the sub-circuit 140 may include a gate synchronous transistor and a constant voltage synchronous transistor. Figure 8 and Fig. 9 This embodiment is described.

[0053] In an exemplary embodiment, the synchronization control signal CTLS (e.g., a source synchronization control signal, a gate synchronization control signal, a constant voltage synchronization control signal, etc.) may be a signal whose activation states do not overlap, such as a scan signal SS (e.g., a previous scan signal SS(n-1), a current scan signal SS(n), a next scan signal SS(n+1)), an emission control signal ES (e.g., a previous emission control signal ES(n-1), a current emission control signal ES(n), a next emission control signal ES(n+1)), etc. In this case, there is an advantage that no additional wiring for applying the synchronization control signal CTLS needs to be formed. In another exemplary embodiment, the synchronization control signal CTLS may be a signal independent of the scan signal SS, the emission control signal ES, etc. In this case, there is an advantage that the synchronization control signal CTLS can be applied in various ways. In short, the pixel circuit 100 can selectively shift the threshold voltage of the driving transistor according to the operation stage and / or operation condition of the organic light-emitting display device by including at least two selected from a source synchronous transistor, a gate synchronous transistor, and a constant voltage synchronous transistor, wherein the source synchronous transistor is electrically connected between the source electrode of the driving transistor and the bottom metal electrode of the driving transistor and is turned on or off in response to a source synchronous control signal, the gate synchronous transistor is electrically connected between the gate electrode of the driving transistor and the bottom metal electrode of the driving transistor and is turned on or off in response to a gate synchronous control signal, and the constant voltage synchronous transistor is electrically connected between the bottom metal electrode of the driving transistor and a constant voltage supply line and is turned on or off in response to a constant voltage synchronous control signal. Therefore, the organic light-emitting display device including the pixel circuit 100 can change the synchronous operation (or reverse bias operation) performed on the driving transistor included in the pixel circuit 100 according to the operation stage and / or operation condition of the organic light-emitting display device. As a result, the organic light emitting display device can selectively utilize the various advantages of synchronous operation (i.e., source synchronous operation, gate synchronous operation, and constant voltage synchronous operation) according to its operational requirements (e.g., reducing the instantaneous afterimage of the organic light emitting display device, increasing the emission brightness of the organic light emitting display device, etc.).

[0054] Figure 2 It is shown Figure 1 FIG. 1 is a diagram of an example of a pixel circuit, Figure 3 It is shown that the Figure 1 A cross-sectional view of an example of the structure of a driving transistor in a pixel circuit.

[0055] Reference Figure 2 and Figure 3 , the pixel circuit 100 - 1 may include a main circuit 120 and a sub-circuit 140 - 1 .

[0056] The main circuit 120 may have a 3T-1C structure (i.e., a structure including three transistors ST, DT, and ET and one capacitor CST). Specifically, the main circuit 120 may include an organic light emitting element OLED, a switching transistor ST, a storage capacitor CST, a driving transistor DT, and an emission control transistor ET, the switching transistor ST being turned on or off in response to a scan signal SS, the storage capacitor CST storing a data signal DS applied via a data line when the switching transistor ST is turned on in response to the scan signal SS, the driving transistor DT allowing a driving current corresponding to the data signal DS stored in the storage capacitor CST to flow into the organic light emitting element OLED, and the emission control transistor ET being electrically connected in series to the organic light emitting element OLED and the driving transistor DT between a high power supply voltage ELVDD and a low power supply voltage ELVSS and being turned on or off in response to an emission control signal ES. In an exemplary embodiment, as Figure 2 As shown in , the organic light emitting element OLED may include an anode electrically connected to the second node N2 and a cathode to which the low power supply voltage ELVSS is applied. The switching transistor ST may include a first electrode to which a data signal DS is applied, a second electrode electrically connected to the first node N1, and a gate electrode to which a scan signal SS is applied. The storage capacitor CST may include a first electrode electrically connected to the first node N1 and a second electrode electrically connected to the second node N2. The driving transistor DT may include a first electrode electrically connected to the second electrode of the emission control transistor ET (i.e., Figure 3 The source electrode 60 in the embodiment of the present invention is connected to the second electrode (ie, Figure 3 The drain electrode 70 in the embodiment of the present invention is electrically connected to the gate electrode (ie, Figure 3 The gate electrode 90 in the embodiment of the present invention) and the bottom metal electrode (ie, Figure 3 The emission control transistor ET may include a first electrode to which a high power supply voltage ELVDD is applied, a first electrode electrically connected to the driving transistor DT (ie, Figure 3 A second electrode of the source electrode 60 in the embodiment and a gate electrode to which the emission control signal ES is applied.

[0057] although Figure 2The main circuit 120 is shown to include an organic light emitting element OLED, a switching transistor ST, a storage capacitor CST, a driving transistor DT, and an emission control transistor ET, but it should be understood that only the necessary components for the operation of the main circuit 120 (i.e., the organic light emitting element OLED, the switching transistor ST, the storage capacitor CST, the driving transistor DT, and the emission control transistor ET) are mentioned. That is, the main circuit 120 may also include other components in addition to the organic light emitting element OLED, the switching transistor ST, the storage capacitor CST, the driving transistor DT, and the emission control transistor ET. For example, the main circuit 120 may also include a component for compensating for the threshold voltage of the driving transistor DT and / or a component for initializing the nodes N1 and N2. In addition, although the connections between the components of the main circuit 120 (i.e., the organic light emitting element OLED, the switching transistor ST, the storage capacitor CST, the driving transistor DT, and the emission control transistor ET) are shown as examples, the connections between the components of the main circuit 120 are not limited thereto. For example, when the main circuit 120 further includes a component for compensating for the threshold voltage of the driving transistor DT and / or a component for initializing the nodes N1 and N2, the connection between the organic light emitting element OLED, the switching transistor ST, the storage capacitor CST, the driving transistor DT, and the emission control transistor ET may be changed to form a connection between the organic light emitting element OLED, the switching transistor ST, the storage capacitor CST, the driving transistor DT, the emission control transistor ET, and the additional components. In addition, although Figure 2 The transistors ST, DT, and ET included in the main circuit 120 are shown to be PMOS transistors, but are not limited thereto. For example, each of the transistors ST, DT, and ET included in the main circuit 120 may be an NMOS transistor or a PMOS transistor.

[0058] like Figure 2 As shown in FIG. 1 , the driving transistor DT included in the main circuit 120 may be implemented as a PMOS transistor. For example, the driving transistor DT may have a Figure 3The cross-sectional structure shown in . Specifically, the driving transistor DT may have a cross-sectional structure in which a substrate 10, a bottom metal electrode 20, a gate insulating layer 30, an active layer 40, an etching stopper layer 50, a first electrode 60 and a second electrode 70, a gate insulating layer 80 and a gate electrode 90 are sequentially arranged (or formed). The substrate 10 may be a silicon semiconductor substrate, a glass substrate, a plastic substrate, etc. The bottom metal electrode 20 may be formed on the substrate 10. For example, the bottom metal electrode 20 may be formed by depositing a specific metal and patterning the deposited metal. The gate insulating layer 30 may be formed on the bottom metal electrode 20. The gate insulating layer 30 may cover the bottom metal electrode 20. The active layer 40 may be formed on the gate insulating layer 30. The active layer 40 may provide a channel region, a source region, and a drain region. Here, the central region (for example, Figure 3 The area protruding upward in the middle) corresponds to the channel area, and the peripheral area corresponds to the source area and the drain area. The etching stopper layer 50 may be formed on the active layer 40. The etching stopper layer 50 may cover a portion of the active layer 40. The first electrode 60 and the second electrode 70 may be formed on the etching stopper layer 50. The first electrode 60 and the second electrode 70 may contact the source area and the drain area of ​​the active layer 40, respectively. The gate insulating layer 80 may be formed on the etching stopper layer 50 and the first electrode 60 and the second electrode 70. The gate insulating layer 80 may cover the etching stopper layer 50 and the first electrode 60 and the second electrode 70. The gate electrode 90 may be formed on the gate insulating layer 80. For example, the gate electrode 90 may be formed by depositing a specific metal and by patterning the deposited metal. Because Figure 3 The structure of the driving transistor DT shown in is only an example, so the driver transistor DT may have various other cross-sectional structures. In an exemplary embodiment, when the threshold voltage of the driving transistor DT as a PMOS transistor shifts in the negative direction, the on-current of the driving transistor DT (i.e., the current flowing through the driving transistor DT) may be reduced under the same conditions. On the other hand, when the threshold voltage of the driving transistor DT as a PMOS transistor shifts in the positive direction, the on-current of the driving transistor DT may be increased under the same conditions.

[0059] The sub-circuit 140-1 may be electrically connected to the main circuit 120. Specifically, the sub-circuit 140-1 may include a source synchronous transistor SST and a gate synchronous transistor GST. The source synchronous transistor SST may be electrically connected between the first electrode (i.e., source electrode 60) of the driving transistor DT and the bottom metal electrode 20 of the driving transistor DT. The source synchronous transistor SST may be turned on or off in response to a source synchronous control signal SCTL. In an exemplary embodiment, as shown in FIG. Figure 2As shown in , the source synchronous transistor SST can be implemented as a PMOS transistor. In this case, the source synchronous transistor SST can be turned on when the source synchronous control signal SCTL is activated (i.e., when the source synchronous control signal SCTL has a negative voltage level), and the source synchronous transistor SST can be turned off when the source synchronous control signal SCTL is deactivated (i.e., when the source synchronous control signal SCTL has a positive voltage level). In another exemplary embodiment, the source synchronous transistor SST can be implemented as an NMOS transistor. In this case, the source synchronous transistor SST can be turned on when the source synchronous control signal SCTL is activated (i.e., when the source synchronous control signal SCTL has a positive voltage level), and the source synchronous transistor SST can be turned off when the source synchronous control signal SCTL is deactivated (i.e., when the source synchronous control signal SCTL has a negative voltage level). The source synchronous control signal SCTL can be activated during the first period when it is necessary to reduce the driving current flowing into the organic light emitting element OLED (for example, when it is necessary to reduce the instantaneous afterimage of the organic light emitting display device). Therefore, the source synchronous transistor SST can be turned on during the first period, so the source voltage of the first electrode (i.e., the source electrode 60) of the driving transistor DT can be applied to the bottom metal electrode 20 of the driving transistor DT during the first period. As a result, the threshold voltage of the driving transistor DT as a PMOS transistor can be shifted in the negative direction, and thus the driving current (i.e., the leakage current) flowing through the driving transistor DT can be reduced. In other words, when the source synchronous transistor SST is turned on, the threshold voltage of the driving transistor DT as a PMOS transistor can be shifted in the negative direction, so the instantaneous afterimage of the organic light emitting display device can be reduced (or improved) because the leakage current flowing through the driving transistor DT is reduced under the same conditions.

[0060] The gate synchronous transistor GST may be electrically connected between the gate electrode 90 (ie, the first node N1) of the driving transistor DT and the bottom metal electrode 20 of the driving transistor DT. The gate synchronous transistor GST may be turned on or off in response to the gate synchronous control signal GCTL. Figure 2As shown in , the gate synchronous transistor GST can be implemented as a PMOS transistor. In this case, the gate synchronous transistor GST can be turned on when the gate synchronous control signal GCTL is activated (i.e., when the gate synchronous control signal GCTL has a negative voltage level), and the gate synchronous transistor GST can be turned off when the gate synchronous control signal GCTL is deactivated (i.e., when the gate synchronous control signal GCTL has a positive voltage level). In another exemplary embodiment, the gate synchronous transistor GST can be implemented as an NMOS transistor. In this case, the gate synchronous transistor GST can be turned on when the gate synchronous control signal GCTL is activated (i.e., when the gate synchronous control signal GCTL has a positive voltage level), and the gate synchronous transistor GST can be turned off when the gate synchronous control signal GCTL is deactivated (i.e., when the gate synchronous control signal GCTL has a negative voltage level). The gate synchronous control signal GCTL can be activated during the second period when it is necessary to increase the driving current flowing into the organic light emitting element OLED (for example, when it is necessary to increase the emission brightness of the organic light emitting display device). Therefore, the gate synchronous transistor GST can be turned on during the second period, and therefore, the gate voltage of the gate electrode 90 of the driving transistor DT can be applied to the bottom metal electrode 20 of the driving transistor DT during the second period. As a result, the threshold voltage of the driving transistor DT as a PMOS transistor can be shifted in the positive direction, and thus the driving current flowing through the driving transistor DT can be increased. In other words, when the gate synchronous transistor GST is turned on, the threshold voltage of the driving transistor DT as a PMOS transistor can be shifted in the positive direction, and thus the emission brightness of the organic light emitting display device can be increased (or improved) because the driving current flowing through the driving transistor DT increases under the same conditions.

[0061] In short, the pixel circuit 100-1 can selectively shift the threshold voltage of the driving transistor DT according to the operation stage (e.g., initialization stage, threshold voltage compensation stage, data writing stage, light emitting stage, etc.) and / or operation conditions of the organic light emitting display device by including a source synchronous transistor SST and a gate synchronous transistor GST, the source synchronous transistor SST being electrically connected between the first electrode (i.e., source electrode 60) of the driving transistor DT and the bottom metal electrode 20 of the driving transistor DT and being turned on or off in response to the source synchronous control signal SCTL, and the gate synchronous transistor GST being electrically connected between the gate electrode (i.e., first node N1) of the driving transistor DT and the bottom metal electrode 20 of the driving transistor DT and being turned on or off in response to the gate synchronous control signal GCTL. Therefore, the organic light emitting display device including the pixel circuit 100 can change the synchronous operation (or reverse bias operation) performed on the driving transistor DT included in the pixel circuit 100 according to the operation stage and / or operation conditions of the organic light emitting display device. As a result, the organic light emitting display device can selectively utilize the various advantages of synchronous operation (i.e., source synchronous operation, gate synchronous operation, and constant voltage synchronous operation) according to its operational requirements (e.g., reducing the instantaneous afterimage of the organic light emitting display device, increasing the emission brightness of the organic light emitting display device, etc.). For example, the pixel circuit 100-1 can shift the threshold voltage of the driving transistor DT in a first direction (i.e., when the driving transistor DT is a PMOS transistor, the threshold voltage of the driving transistor DT can be shifted in a negative direction) under a first operating condition (or in a first operating stage) by turning on the source synchronous transistor SST to reduce the instantaneous afterimage of the organic light-emitting display device; the pixel circuit 100-1 can shift the threshold voltage of the driving transistor DT in a second direction (i.e., when the driving transistor DT is a PMOS transistor, the threshold voltage of the driving transistor DT can be shifted in a positive direction) under a second operating condition (or in a second operating stage) by turning on the gate synchronous transistor GST to increase the emission brightness of the organic light-emitting display device; and the pixel circuit 100-1 can not shift the threshold voltage of the driving transistor DT under a third operating condition (or in a third operating stage) by turning off the source synchronous transistor SST and the gate synchronous transistor GST. Although in Figure 2, the main circuit 120 is shown to have a 3T-1C structure (i.e., a structure including three transistors ST, DT, and ET and a capacitor CST), but the structure of the main circuit 120 is not limited thereto. For example, the main circuit 120 may have various structures (e.g., a 7T-1C structure) according to the requirements of the organic light-emitting display device. In an exemplary embodiment, the source synchronization control signal SCTL and the gate synchronization control signal GCTL may be signals whose activation states do not overlap, such as a scan signal SS (e.g., a previous scan signal SS (n-1), a current scan signal SS (n), a next scan signal SS (n+1)), an emission control signal ES (e.g., a previous emission control signal ES (n-1), a current emission control signal ES (n), a next emission control signal ES (n+1)), etc. In another exemplary embodiment, the source synchronization control signal SCTL and the gate synchronization control signal GCTL may be signals independent of the scan signal SS, the emission control signal ES, etc.

[0062] Figure 4 It is shown Figure 1 FIG. 1 is a diagram of another example of a pixel circuit of FIG.

[0063] Reference Figure 4 , the pixel circuit 100-2 may include a main circuit 120 and a sub-circuit 140-2. The sub-circuit 140-2 further includes a constant voltage synchronous transistor EST, but in other aspects the pixel circuit 100-2 may be similar to Figure 2 Therefore, the following description will focus on the constant voltage synchronous transistor EST included in the pixel circuit 100-2 to describe the pixel circuit 100-2. Figure 4 As shown in , the driving transistor DT may be a PMOS transistor.

[0064] The sub-circuit 140-2 may include a source synchronous transistor SST, a gate synchronous transistor GST, and a constant voltage synchronous transistor EST. The constant voltage synchronous transistor EST may be electrically connected between the bottom metal electrode 20 of the driving transistor DT and a constant voltage supply line for transmitting a constant voltage SV. The constant voltage synchronous transistor EST may be turned on or off in response to a constant voltage synchronous control signal ECTL. In an exemplary embodiment, as shown in FIG. Figure 4As shown in , the constant voltage synchronous transistor EST can be implemented as a PMOS transistor. In this case, the constant voltage synchronous transistor EST can be turned on when the constant voltage synchronous control signal ECTL is activated (i.e., when the constant voltage synchronous control signal ECTL has a negative voltage level), and the constant voltage synchronous transistor EST can be turned off when the constant voltage synchronous control signal ECTL is deactivated (i.e., when the constant voltage synchronous control signal ECTL has a positive voltage level). In another exemplary embodiment, the constant voltage synchronous transistor EST can be implemented as an NMOS transistor. In this case, the constant voltage synchronous transistor EST can be turned on when the constant voltage synchronous control signal ECTL is activated (i.e., when the constant voltage synchronous control signal ECTL has a positive voltage level), and the constant voltage synchronous transistor EST can be turned off when the constant voltage synchronous control signal ECTL is deactivated (i.e., when the constant voltage synchronous control signal ECTL has a negative voltage level).

[0065] In an exemplary embodiment, the constant voltage SV supplied via the constant voltage supply line may have a positive voltage level. For example, the constant voltage SV may be a high power supply voltage ELVDD, and the constant voltage supply line may be a line that transmits the high power supply voltage ELVDD. In this case, when the constant voltage synchronous transistor EST is turned on in response to the constant voltage synchronous control signal ECTL, the threshold voltage of the driving transistor DT may be shifted in the negative direction. Therefore, the constant voltage synchronous control signal ECTL may be activated during the third period when the driving current flowing into the organic light emitting element OLED needs to be reduced (for example, when the instantaneous afterimage of the organic light emitting display device needs to be reduced). Therefore, the constant voltage synchronous transistor EST may be turned on during the third period, so that the constant voltage SV having a positive voltage level (for example, the high power supply voltage ELVDD) may be applied to the bottom metal electrode 20 of the driving transistor DT during the third period. As a result, the threshold voltage of the driving transistor DT, which is a PMOS transistor, may be shifted in the negative direction, so that the driving current (i.e., the leakage current) flowing through the driving transistor DT may be reduced. In other words, when the constant voltage synchronous transistor EST is turned on, the threshold voltage of the driving transistor DT as a PMOS transistor can be shifted in the negative direction, and the instantaneous afterimage of the organic light emitting display device can be reduced (or improved) because the leakage current flowing through the driving transistor DT is reduced under the same conditions.

[0066] In another exemplary embodiment, the constant voltage SV supplied via the constant voltage supply line may have a negative voltage level. For example, the constant voltage SV may be a low power supply voltage ELVSS, and the constant voltage supply line may be a line that transmits the low power supply voltage ELVSS. In this case, when the constant voltage synchronous transistor EST is turned on in response to the constant voltage synchronous control signal ECTL, the threshold voltage of the driving transistor DT may be shifted in the positive direction. Therefore, the constant voltage synchronous control signal ECTL may be activated during the fourth period when the driving current flowing into the organic light emitting element OLED needs to be increased (for example, when the emission brightness of the organic light emitting display device needs to be increased). Therefore, the constant voltage synchronous transistor EST may be turned on during the fourth period, so that the constant voltage SV having a negative voltage level may be applied to the bottom metal electrode 20 of the driving transistor DT during the fourth period. As a result, the threshold voltage of the driving transistor DT, which is a PMOS transistor, may be shifted in the positive direction, so that the driving current flowing through the driving transistor DT may be increased. In other words, when the constant voltage synchronous transistor EST is turned on, the threshold voltage of the driving transistor DT as a PMOS transistor can be shifted in the positive direction, so the emission brightness of the organic light emitting display device can be increased (or improved) because the driving current flowing through the driving transistor DT increases under the same conditions.

[0067] In short, the pixel circuit 100-2 can selectively shift the threshold voltage of the driving transistor DT according to the operating stage and / or operating conditions of the organic light-emitting display device by including a source synchronous transistor SST, a gate synchronous transistor GST and a constant voltage synchronous transistor EST, wherein the source synchronous transistor SST is electrically connected between the source electrode 60 of the driving transistor DT and the bottom metal electrode 20 of the driving transistor DT and is turned on or off in response to the source synchronous control signal SCTL, the gate synchronous transistor GST is electrically connected between the gate electrode of the driving transistor DT and the bottom metal electrode 20 of the driving transistor DT and is turned on or off in response to the gate synchronous control signal GCTL, and the constant voltage synchronous transistor EST is electrically connected between the bottom metal electrode 20 of the driving transistor DT and the constant voltage supply line and is turned on or off in response to the constant voltage synchronous control signal ECTL. For example, the pixel circuit 100-2 can shift the threshold voltage of the driving transistor DT in a first direction (i.e., when the driving transistor DT is a PMOS transistor, the threshold voltage of the driving transistor DT can be shifted in a negative direction) under a first operating condition (or in a first operating stage) by turning on the source synchronous transistor SST or the constant voltage synchronous transistor EST (i.e., when the constant voltage SV has a positive voltage level) to reduce the instantaneous afterimage of the organic light-emitting display device; the pixel circuit 100-2 can shift the threshold voltage of the driving transistor DT in a second direction (i.e., when the driving transistor DT is a PMOS transistor, the threshold voltage of the driving transistor DT can be shifted in a positive direction) under a second operating condition (or in a second operating stage) by turning on the gate synchronous transistor GST or the constant voltage synchronous transistor EST (i.e., when the constant voltage SV has a negative voltage level) to increase the emission brightness of the organic light-emitting display device; and the pixel circuit 100-2 can not shift the threshold voltage of the driving transistor DT under a third operating condition (or in a third operating stage) by turning off the source synchronous transistor SST, the gate synchronous transistor GST and the constant voltage synchronous transistor EST.

[0068] Figure 5 It is shown Figure 1 FIG. 1 is a diagram of yet another example of a pixel circuit.

[0069] Reference Figure 5 , the pixel circuit 100-3 may include a main circuit 120 and a sub-circuit 140-3. The sub-circuit 140-3 further includes a first constant voltage synchronous transistor EST1 and a second constant voltage synchronous transistor EST2, but in other aspects the pixel circuit 100-3 may be similar to Figure 2 Therefore, the following description will focus on the first constant voltage synchronous transistor EST1 and the second constant voltage synchronous transistor EST2 included in the pixel circuit 100-3 to describe the pixel circuit 100-3. Figure 5As shown in , the driving transistor DT may be a PMOS transistor.

[0070] The sub-circuit 140-3 may include a source synchronous transistor SST, a gate synchronous transistor GST, a first constant voltage synchronous transistor EST1, and a second constant voltage synchronous transistor EST2. The first constant voltage synchronous transistor EST1 may be electrically connected between the bottom metal electrode 20 of the driving transistor DT and the first constant voltage supply line transmitting the first constant voltage SV1. The first constant voltage synchronous transistor EST1 may be turned on or off in response to the first constant voltage synchronous control signal ECTL1. In an exemplary embodiment, as shown in FIG. Figure 5As shown in , the first constant voltage synchronous transistor EST1 can be implemented as a PMOS transistor. In this case, the first constant voltage synchronous transistor EST1 can be turned on when the first constant voltage synchronous control signal ECTL1 is activated (i.e., when the first constant voltage synchronous control signal ECTL1 has a negative voltage level), and the first constant voltage synchronous transistor EST1 can be turned off when the first constant voltage synchronous control signal ECTL1 is deactivated (i.e., when the first constant voltage synchronous control signal ECTL1 has a positive voltage level). In another exemplary embodiment, the first constant voltage synchronous transistor EST1 can be implemented as an NMOS transistor. In this case, the first constant voltage synchronous transistor EST1 can be turned on when the first constant voltage synchronous control signal ECTL1 is activated (i.e., when the first constant voltage synchronous control signal ECTL1 has a positive voltage level), and the first constant voltage synchronous transistor EST1 can be turned off when the first constant voltage synchronous control signal ECTL1 is deactivated (i.e., when the first constant voltage synchronous control signal ECTL1 has a negative voltage level). Here, the first constant voltage SV1 supplied via the first constant voltage supply line can have a positive voltage level. For example, the first constant voltage SV1 may be a high power supply voltage ELVDD, and the first constant voltage supply line may be a line for transmitting the high power supply voltage ELVDD. In this case, when the first constant voltage synchronous transistor EST1 is turned on in response to the first constant voltage synchronous control signal ECTL1, the threshold voltage of the driving transistor DT may be shifted in the negative direction. Therefore, the first constant voltage synchronous control signal ECTL1 may be activated during the third period when the driving current flowing into the organic light emitting element OLED needs to be reduced (for example, when the instantaneous afterimage of the organic light emitting display device needs to be reduced). Therefore, the first constant voltage synchronous transistor EST1 may be turned on during the third period, so that the first constant voltage SV1 having a positive voltage level (for example, the high power supply voltage ELVDD) may be applied to the bottom metal electrode 20 of the driving transistor DT during the third period. As a result, the threshold voltage of the driving transistor DT, which is a PMOS transistor, may be shifted in the negative direction, so that the driving current (i.e., the leakage current) flowing through the driving transistor DT may be reduced. In other words, when the first constant voltage synchronous transistor EST1 is turned on, the threshold voltage of the driving transistor DT as a PMOS transistor can be shifted in the negative direction, so the instantaneous afterimage of the organic light emitting display device can be reduced (or improved) because the leakage current flowing through the driving transistor DT is reduced under the same conditions.

[0071] The second constant voltage synchronous transistor EST2 may be electrically connected between the bottom metal electrode 20 of the driving transistor DT and the second constant voltage supply line transmitting the second constant voltage SV2. The second constant voltage synchronous transistor EST2 may be turned on or off in response to the second constant voltage synchronous control signal ECTL2. In an exemplary embodiment, as shown in FIG. Figure 5As shown in , the second constant voltage synchronous transistor EST2 can be implemented as a PMOS transistor. In this case, the second constant voltage synchronous transistor EST2 can be turned on when the second constant voltage synchronous control signal ECTL2 is activated (i.e., when the second constant voltage synchronous control signal ECTL2 has a negative voltage level), and the second constant voltage synchronous transistor EST2 can be turned off when the second constant voltage synchronous control signal ECTL2 is deactivated (i.e., when the second constant voltage synchronous control signal ECTL2 has a positive voltage level). In another exemplary embodiment, the second constant voltage synchronous transistor EST2 can be implemented as an NMOS transistor. In this case, the second constant voltage synchronous transistor EST2 can be turned on when the second constant voltage synchronous control signal ECTL2 is activated (i.e., when the second constant voltage synchronous control signal ECTL2 has a positive voltage level), and the second constant voltage synchronous transistor EST2 can be turned off when the second constant voltage synchronous control signal ECTL2 is deactivated (i.e., when the second constant voltage synchronous control signal ECTL2 has a negative voltage level). The second constant voltage SV2 supplied via the second constant voltage supply line can have a negative voltage level. For example, the second constant voltage SV2 may be a low power supply voltage ELVSS, and the second constant voltage supply line may be a line for transmitting the low power supply voltage ELVSS. In this case, when the second constant voltage synchronous transistor EST2 is turned on in response to the second constant voltage synchronous control signal ECTL2, the threshold voltage of the driving transistor DT may be shifted in the positive direction. Therefore, the second constant voltage synchronous control signal ECTL2 may be activated during the fourth period when the driving current flowing into the organic light emitting element OLED needs to be increased (for example, when the emission brightness of the organic light emitting display device needs to be increased). Therefore, the second constant voltage synchronous transistor EST2 may be turned on during the fourth period, so that the second constant voltage SV2 having a negative voltage level may be applied to the bottom metal electrode 20 of the driving transistor DT during the fourth period. As a result, the threshold voltage of the driving transistor DT, which is a PMOS transistor, may be shifted in the positive direction, and therefore, the driving current flowing through the driving transistor DT may be increased. In other words, when the second constant voltage synchronous transistor EST2 is turned on, the threshold voltage of the driving transistor DT as a PMOS transistor can be shifted in the positive direction, so the emission brightness of the organic light-emitting display device can be increased (or improved) because the driving current flowing through the driving transistor DT increases under the same conditions.

[0072] The pixel circuit 100-3 can selectively shift the threshold voltage of the driving transistor DT according to the operating stage and / or operating conditions of the organic light-emitting display device by including a source synchronous transistor SST, a gate synchronous transistor GST, a first constant voltage synchronous transistor EST1 and a second constant voltage synchronous transistor EST2, wherein the source synchronous transistor SST is electrically connected between the source electrode 60 of the driving transistor DT and the bottom metal electrode 20 of the driving transistor DT and is turned on or off in response to a source synchronous control signal SCTL, the gate synchronous transistor GST is electrically connected between the gate electrode of the driving transistor DT and the bottom metal electrode 20 of the driving transistor DT and is turned on or off in response to a gate synchronous control signal GCTL, the first constant voltage synchronous transistor EST1 is electrically connected between the bottom metal electrode 20 of the driving transistor DT and the first constant voltage supply line and is turned on or off in response to the first constant voltage synchronous control signal ECTL1, and the second constant voltage synchronous transistor EST2 is electrically connected between the bottom metal electrode 20 of the driving transistor DT and the second constant voltage supply line and is turned on or off in response to the second constant voltage synchronous control signal ECTL2. For example, the pixel circuit 100-3 can shift the threshold voltage of the driving transistor DT in a first direction (i.e., when the driving transistor DT is a PMOS transistor, the threshold voltage of the driving transistor DT can be shifted in a negative direction) under a first operating condition (or in a first operating stage) by turning on the source synchronous transistor SST or the first constant-voltage synchronous transistor EST1 to reduce the instantaneous afterimage of the organic light-emitting display device; the pixel circuit 100-3 can shift the threshold voltage of the driving transistor DT in a second direction (i.e., when the driving transistor DT is a PMOS transistor, the threshold voltage of the driving transistor DT can be shifted in a positive direction) under a second operating condition (or in a second operating stage) by turning on the gate synchronous transistor GST or the second constant-voltage synchronous transistor EST2 to increase the emission brightness of the organic light-emitting display device; and the pixel circuit 100-3 can not shift the threshold voltage of the driving transistor DT under a third operating condition (or in a third operating stage) by turning off the source synchronous transistor SST, the gate synchronous transistor GST, the first constant-voltage synchronous transistor EST1, and the second constant-voltage synchronous transistor EST2.

[0073] Figure 6 It is shown Figure 1 FIG. 1 is a diagram of yet another example of a pixel circuit.

[0074] Reference Figure 6 , the pixel circuit 100-4 may include a main circuit 120 and a sub-circuit 140-4. The sub-circuit 140-4 does not include a gate synchronous transistor GST, but in other aspects the pixel circuit 100-4 may be similar to Figure 4That is, the sub-circuit 140-4 of the pixel circuit 100-4 may include a source synchronous transistor SST and a constant voltage synchronous transistor EST. Figure 6 As shown in , the driving transistor DT can be a PMOS transistor. The source synchronous transistor SST can be electrically connected between the source electrode 60 of the driving transistor DT and the bottom metal electrode 20 of the driving transistor DT. The source synchronous transistor SST can be turned on or off in response to the source synchronous control signal SCTL. The constant voltage synchronous transistor EST can be electrically connected between the bottom metal electrode 20 of the driving transistor DT and the constant voltage supply line that transmits the constant voltage SV. The constant voltage synchronous transistor EST can be turned on or off in response to the constant voltage synchronous control signal ECTL. Here, the constant voltage SV can have a positive voltage level (e.g., a high power supply voltage ELVDD) or a negative voltage level. Since the source synchronous transistor SST and the constant voltage synchronous transistor EST are described above, the repeated description related thereto will not be repeated. In short, the pixel circuit 100-4 can selectively shift the threshold voltage of the driving transistor DT according to the operating stage and / or operating conditions of the organic light-emitting display device by including the source synchronous transistor SST and the constant voltage synchronous transistor EST. For example, the pixel circuit 100-4 can shift the threshold voltage of the driving transistor DT in a first direction (i.e., when the driving transistor DT is a PMOS transistor, the threshold voltage of the driving transistor DT can be shifted in a negative direction) under a first operating condition (or in a first operating stage) by turning on the source synchronous transistor SST or the constant voltage synchronous transistor EST (i.e., when the constant voltage SV has a positive voltage level) to reduce the instantaneous afterimage of the organic light-emitting display device; the pixel circuit 100-4 can shift the threshold voltage of the driving transistor DT in a second direction (i.e., when the constant voltage SV has a negative voltage level) by turning on the constant voltage synchronous transistor EST (i.e., when the constant voltage SV has a negative voltage level) to increase the emission brightness of the organic light-emitting display device, and the pixel circuit 100-4 can not shift the threshold voltage of the driving transistor DT under a third operating condition (or in a third operating stage) by turning off the source synchronous transistor SST and the constant voltage synchronous transistor EST.

[0075] Figure 7 It is shown Figure 1 FIG. 1 is a diagram of yet another example of a pixel circuit.

[0076] Reference Figure 7 , the pixel circuit 100-5 may include a main circuit 120 and a sub-circuit 140-5. The sub-circuit 140-5 does not include a gate synchronous transistor GST, but in other aspects the pixel circuit 100-5 may be similar to Figure 5That is, the sub-circuit 140-5 of the pixel circuit 100-5 may include a source synchronous transistor SST, a first constant voltage synchronous transistor EST1, and a second constant voltage synchronous transistor EST2. Figure 7 As shown in , the driving transistor DT may be a PMOS transistor. The source synchronous transistor SST may be electrically connected between the source electrode 60 of the driving transistor DT and the bottom metal electrode 20 of the driving transistor DT. The source synchronous transistor SST may be turned on or off in response to the source synchronous control signal SCTL. The first constant voltage synchronous transistor EST1 may be electrically connected between the bottom metal electrode 20 of the driving transistor DT and the first constant voltage supply line transmitting the first constant voltage SV1. The first constant voltage synchronous transistor EST1 may be turned on or off in response to the first constant voltage synchronous control signal ECTL1. Here, the first constant voltage SV1 may have a positive voltage level (e.g., a high power supply voltage ELVDD). The second constant voltage synchronous transistor EST2 may be electrically connected between the bottom metal electrode 20 of the driving transistor DT and the second constant voltage supply line transmitting the second constant voltage SV2. The second constant voltage synchronous transistor EST2 may be turned on or off in response to the second constant voltage synchronous control signal ECTL2. Here, the second constant voltage SV2 may have a negative voltage level. Since the source synchronous transistor SST, the first constant voltage synchronous transistor EST1 and the second constant voltage synchronous transistor EST2 are described above, the repeated description related thereto will not be repeated. In short, the pixel circuit 100-5 can selectively shift the threshold voltage of the driving transistor DT according to the operation stage and / or operation condition of the organic light emitting display device by including the source synchronous transistor SST, the first constant voltage synchronous transistor EST1 and the second constant voltage synchronous transistor EST2. For example, the pixel circuit 100-5 can shift the threshold voltage of the driving transistor DT in a first direction (i.e., when the driving transistor DT is a PMOS transistor, the threshold voltage of the driving transistor DT can be shifted in a negative direction) under a first operating condition (or in a first operating stage) by turning on the source synchronous transistor SST or the first constant-voltage synchronous transistor EST1 to reduce the instantaneous afterimage of the organic light-emitting display device; the pixel circuit 100-5 can shift the threshold voltage of the driving transistor DT in a second direction (i.e., when the driving transistor DT is a PMOS transistor, the threshold voltage of the driving transistor DT can be shifted in a positive direction) under a second operating condition (or in a second operating stage) by turning on the second constant-voltage synchronous transistor EST2 to increase the emission brightness of the organic light-emitting display device; and the pixel circuit 100-5 can not shift the threshold voltage of the driving transistor DT under a third operating condition (or in a third operating stage) by turning off the source synchronous transistor SST, the first constant-voltage synchronous transistor EST1, and the second constant-voltage synchronous transistor EST2.

[0077] Figure 8 It is shown Figure 1 FIG. 1 is a diagram of yet another example of a pixel circuit.

[0078] Reference Figure 8 , the pixel circuit 100-6 may include a main circuit 120 and a sub-circuit 140-6. The sub-circuit 140-6 does not include a source synchronous transistor SST, but in other aspects the pixel circuit 100-6 may be similar to Figure 4 That is, the sub-circuit 140-6 of the pixel circuit 100-6 may include a gate synchronous transistor GST and a constant voltage synchronous transistor EST. Figure 8 As shown in , the driving transistor DT may be a PMOS transistor. The gate synchronous transistor GST may be electrically connected between the gate electrode (i.e., the first node N1) of the driving transistor DT and the bottom metal electrode 20 of the driving transistor DT. The gate synchronous transistor GST may be turned on or off in response to the gate synchronization control signal GCTL. The constant voltage synchronous transistor EST may be electrically connected between the bottom metal electrode 20 of the driving transistor DT and the constant voltage supply line for transmitting the constant voltage SV. The constant voltage synchronous transistor EST may be turned on or off in response to the constant voltage synchronization control signal ECTL. Here, the constant voltage SV may have a positive voltage level (e.g., a high power supply voltage ELVDD) or a negative voltage level. Since the gate synchronous transistor GST and the constant voltage synchronous transistor EST are described above, the repeated description related thereto will not be repeated. In short, the pixel circuit 100-6 may selectively shift the threshold voltage of the driving transistor DT according to the operating phase and / or operating conditions of the organic light emitting display device by including the gate synchronous transistor GST and the constant voltage synchronous transistor EST. For example, the pixel circuit 100-6 can shift the threshold voltage of the driving transistor DT in a first direction (i.e., when the driving transistor DT is a PMOS transistor, the threshold voltage of the driving transistor DT can be shifted in a negative direction) under a first operating condition (or in a first operating stage) by turning on the constant voltage synchronous transistor EST (i.e., when the constant voltage SV has a positive voltage level) to reduce the instantaneous afterimage of the organic light-emitting display device; the pixel circuit 100-6 can shift the threshold voltage of the driving transistor DT in a second direction (i.e., when the driving transistor DT is a PMOS transistor, the threshold voltage of the driving transistor DT can be shifted in a positive direction) under a second operating condition (or in a second operating stage) by turning on the gate synchronous transistor GST or the constant voltage synchronous transistor EST (i.e., when the constant voltage SV has a negative voltage level) to increase the emission brightness of the organic light-emitting display device; and the pixel circuit 100-6 can not shift the threshold voltage of the driving transistor DT under a third operating condition (or in a third operating stage) by turning off the gate synchronous transistor GST and the constant voltage synchronous transistor EST.

[0079] Fig. 9 It is shown Figure 1 FIG. 1 is a diagram of yet another example of a pixel circuit.

[0080] Reference Fig. 9 , the pixel circuit 100-7 may include a main circuit 120 and a sub-circuit 140-7. The sub-circuit 140-7 does not include a source synchronous transistor SST, but in other aspects the pixel circuit 100-7 may be similar to Figure 5 That is, the sub-circuit 140-7 of the pixel circuit 100-7 may include a gate synchronous transistor GST, a first constant voltage synchronous transistor EST1, and a second constant voltage synchronous transistor EST2. Fig. 9As shown in , the driving transistor DT may be a PMOS transistor. The gate synchronous transistor GST may be electrically connected between the gate electrode (i.e., the first node N1) of the driving transistor DT and the bottom metal electrode 20 of the driving transistor DT. The gate synchronous transistor GST may be turned on or off in response to the gate synchronization control signal GCTL. The first constant voltage synchronous transistor EST1 may be electrically connected between the bottom metal electrode 20 of the driving transistor DT and the first constant voltage supply line transmitting the first constant voltage SV1. The first constant voltage synchronous transistor EST1 may be turned on or off in response to the first constant voltage synchronization control signal ECTL1. Here, the first constant voltage SV1 may have a positive voltage level (e.g., a high power supply voltage ELVDD). The second constant voltage synchronous transistor EST2 may be electrically connected between the bottom metal electrode 20 of the driving transistor DT and the second constant voltage supply line transmitting the second constant voltage SV2. The second constant voltage synchronous transistor EST2 may be turned on or off in response to the second constant voltage synchronization control signal ECTL2. Here, the second constant voltage SV2 may have a negative voltage level. Since the gate synchronous transistor GST, the first constant voltage synchronous transistor EST1 and the second constant voltage synchronous transistor EST2 are described above, the repeated description related thereto will not be repeated. In short, the pixel circuit 100-7 can selectively shift the threshold voltage of the driving transistor DT according to the operation stage and / or operation condition of the organic light emitting display device by including the gate synchronous transistor GST, the first constant voltage synchronous transistor EST1 and the second constant voltage synchronous transistor EST2. For example, the pixel circuit 100-7 can shift the threshold voltage of the driving transistor DT in a first direction (i.e., when the driving transistor DT is a PMOS transistor, the threshold voltage of the driving transistor DT can be shifted in a negative direction) by turning on the first constant-voltage synchronous transistor EST1 under a first operating condition (or in a first operating stage) to reduce the instantaneous afterimage of the organic light-emitting display device; the pixel circuit 100-7 can shift the threshold voltage of the driving transistor DT in a second direction (i.e., when the driving transistor DT is a PMOS transistor, the threshold voltage of the driving transistor DT can be shifted in a positive direction) by turning on the gate synchronous transistor GST or the second constant-voltage synchronous transistor EST2 under a second operating condition (or in a second operating stage) to increase the emission brightness of the organic light-emitting display device; and the pixel circuit 100-7 can not shift the threshold voltage of the driving transistor DT by turning off the gate synchronous transistor GST, the first constant-voltage synchronous transistor EST1, and the second constant-voltage synchronous transistor EST2 under a third operating condition (or in a third operating stage).

[0081] Fig.10 is a block diagram illustrating an organic light emitting display device according to an exemplary embodiment.

[0082] Reference Fig.10The organic light emitting display device 500 may include a display panel 510 , a data driver 520 , a scan driver 530 , an emission control driver 540 , and a timing controller 560 . In some exemplary embodiments, the organic light emitting display device 500 may further include a synchronization control driver 550 .

[0083] The display panel 510 may include a plurality of pixel circuits 511. The display panel 510 may be connected to a data driver 520 via a plurality of data lines. The display panel 510 may be connected to a scan driver 530 via a plurality of scan lines. The display panel 510 may be connected to an emission control driver 540 via a plurality of emission control lines. The data driver 520 may provide a data signal DS to the display panel 510 via the data lines. That is, the data driver 520 may provide a data signal DS to the pixel circuit 511. The scan driver 530 may provide a scan signal SS to the display panel 510 via the scan lines. That is, the scan driver 530 may provide a scan signal SS to the pixel circuit 511. The emission control driver 540 may provide an emission control signal ES to the display panel 510 via the emission control lines. That is, the emission control driver 540 may provide an emission control signal ES to the pixel circuit 511. In an exemplary embodiment, the synchronization control signal CTLS (e.g., a source synchronization control signal, a gate synchronization control signal, a constant voltage synchronization control signal, etc.) may be determined as a signal independent of the scan signal SS (e.g., a previous scan signal SS(n-1), a current scan signal SS(n), a next scan signal SS(n+1)), the emission control signal ES (e.g., a previous emission control signal ES(n-1), a current emission control signal ES(n), a next emission control signal ES(n+1)), etc. In this case, the organic light-emitting display device 500 may include a synchronization control driver 550, and the synchronization control driver 550 may provide the synchronization control signal CTLS to the display panel 510. That is, the synchronization control driver 550 may provide the synchronization control signal CTLS to the pixel circuit 511. In another exemplary embodiment, the synchronization control signal CTLS (e.g., a source synchronization control signal, a gate synchronization control signal, a constant voltage synchronization control signal, etc.) may be determined as a signal whose activation states do not overlap, such as the scan signal SS, the emission control signal ES, etc. In this case, the organic light-emitting display device 500 may not include the synchronization control driver 550. The timing controller 560 may control the scan driver 530, the data driver 520, the emission control driver 540, and the synchronization control driver 550 by generating a plurality of control signals CTL(1), CTL(2), CTL(3), and CTL(4) and providing the plurality of control signals CTL(1), CTL(2), CTL(3), and CTL(4) to the scan driver 530, the data driver 520, the emission control driver 540, and the synchronization control driver 550, respectively. The timing controller 560 may receive image data and perform specific data processing (e.g., degradation compensation, etc.) on the image data.

[0084] In an exemplary embodiment, the pixel circuit 511 included in the display panel 510 may include a main circuit and a sub-circuit electrically connected to the main circuit. The main circuit may receive a data signal DS in response to a scan signal SS, and may output light having a brightness corresponding to the data signal DS in response to an emission control signal ES. In an exemplary embodiment, the main circuit may include an organic light emitting element, a switching transistor, a storage capacitor, a driving transistor, and an emission control transistor. In some exemplary embodiments, the main circuit may also include other components in addition to the component (i.e., the organic light emitting element, the switching transistor, the storage capacitor, the driving transistor, and the emission control transistor). The sub-circuit may receive a synchronization control signal CTLS, and may selectively shift the threshold voltage of the driving transistor included in the main circuit based on the synchronization control signal CTLS. For example, the sub-circuit may shift the threshold voltage of the driving transistor in a first direction so as to reduce (or improve) the instantaneous afterimage of the organic light emitting display device 500; the sub-circuit may shift the threshold voltage of the driving transistor in a second direction opposite to the first direction so as to increase (or improve) the emission brightness of the organic light emitting display device 500; and the sub-circuit may not shift the threshold voltage of the driving transistor. In other words, the sub-circuit may selectively shift the threshold voltage of the driving transistor according to the operation stage and / or operation condition of the organic light-emitting display device 500. To this end, the sub-circuit may include at least two selected from a source synchronous transistor, a gate synchronous transistor, and a constant voltage synchronous transistor, the source synchronous transistor being electrically connected between the source electrode of the driving transistor and the bottom metal electrode of the driving transistor and being turned on or off in response to a source synchronous control signal, the gate synchronous transistor being electrically connected between the gate electrode of the driving transistor and the bottom metal electrode of the driving transistor and being turned on or off in response to a gate synchronous control signal, and the constant voltage synchronous transistor being electrically connected between the bottom metal electrode of the driving transistor and a constant voltage supply line and being turned on or off in response to a constant voltage synchronous control signal. In short, the organic light-emitting display device 500 can selectively utilize the advantages of synchronous operation (i.e., source synchronous operation, gate synchronous operation, and constant voltage synchronous operation) according to the operation requirements of the organic light-emitting display device 500 (e.g., reducing the instantaneous afterimage of the organic light-emitting display device 500, increasing the emission brightness of the organic light-emitting display device 500, etc.) by including a pixel circuit 511, and the pixel circuit 511 can selectively shift the threshold voltage of the driving transistor according to the operation stage and / or operation condition of the organic light-emitting display device 500, wherein the pixel circuit 511 includes at least two of the source synchronous transistor, the gate synchronous transistor, and the constant voltage synchronous transistor. Therefore, the organic light-emitting display device 500 can provide a high-quality image to the viewer. Since these exemplary embodiments are described above, the repeated description related thereto will not be repeated.

[0085] Fig.11is a block diagram illustrating an electronic device according to an exemplary embodiment, Fig.12 It is shown Fig.11 The electronic device is implemented as an example of a smart phone.

[0086] Reference Fig.11 and Fig.12 , the electronic device 1000 may include a processor 1010, a memory device 1020, a storage device 1030, an input / output (I / O) device 1040, a power supply 1050, and an organic light emitting display device 1060. Here, the organic light emitting display device 1060 may be Fig.10 In addition, the electronic device 1000 may further include a plurality of ports for communicating with a video card, a sound card, a memory card, a universal serial bus (USB) device, other electronic devices, etc. In an exemplary embodiment, as Fig.12 As shown in , the electronic device 1000 may be implemented as a smart phone. However, the electronic device 1000 is not limited thereto. For example, the electronic device 1000 may be implemented as a cellular phone, a video phone, a smart tablet, a smart watch, a tablet PC, a car navigation system, a computer monitor, a laptop computer, a head mounted display (HMD) device, etc.

[0087] The processor 1010 may perform various computing functions. The processor 1010 may be a microprocessor, a central processing unit (CPU), an application processor (AP), etc. The processor 1010 may be coupled to other components via an address bus, a control bus, a data bus, etc. In addition, the processor 1010 may be coupled to an expansion bus such as a peripheral component interconnect (PCI) bus. The memory device 1020 may store data for the operation of the electronic device 1000. For example, the memory device 1020 may include at least one non-volatile memory device (such as an erasable programmable read-only memory (EPROM) device, an electrically erasable programmable read-only memory (EEPROM) device, a flash memory device, a phase change random access memory (PRAM) device, a resistive random access memory (RRAM) device, a nano floating gate memory (NFGM) device, a polymer random access memory (PoRAM) device, a magnetic random access memory (MRAM) device, a ferroelectric random access memory (FRAM) device, etc.) and / or at least one volatile memory device (such as a dynamic random access memory (DRAM) device, a static random access memory (SRAM) device, a mobile DRAM device, etc.). The storage device 1030 may include a solid state drive (SSD) device, a hard disk drive (HDD) device, a CD-ROM device, etc. The I / O device 1040 may include an input device (such as a keyboard, a keypad, a mouse device, a touch pad, a touch screen, etc.) and an output device (such as a printer, a speaker, etc.). In some exemplary embodiments, the I / O device 1040 may include an organic light emitting display device 1060. The power supply 1050 may provide power for operation of the electronic device 1000. The organic light emitting display device 1060 may be coupled to other components via a bus or other communication links.

[0088] As described above, the organic light-emitting display device 1060 can selectively utilize the advantages of synchronous operation (i.e., source synchronous operation, gate synchronous operation, and constant voltage synchronous operation) according to its operating requirements (e.g., reducing the instantaneous afterimage of the organic light-emitting display device 1060, increasing the emission brightness of the organic light-emitting display device 1060, etc.). Therefore, the organic light-emitting display device 1060 can provide high-quality images to viewers. To this end, the organic light-emitting display device 1060 may include a display panel, a data driver, a scan driver, an emission control driver, and a timing controller, the display panel having a plurality of pixel circuits, wherein each of the pixel circuits can selectively shift the threshold voltage of the driving transistor in the pixel circuit according to the operating phase and / or operating conditions of the organic light-emitting display device 1060 by including at least two selected from a source synchronous transistor, a gate synchronous transistor, and a constant voltage synchronous transistor, the data driver provides a data signal to the pixel circuit, the scan driver provides a scan signal to the pixel circuit, the emission control driver provides an emission control signal to the pixel circuit, and the timing controller controls the data driver, the scan driver, and the emission control driver. In some exemplary embodiments, the organic light emitting display device 1060 may further include a synchronous control driver for providing a synchronous control signal (eg, a source synchronous control signal, a gate synchronous control signal, and a constant voltage synchronous control signal) to the pixel circuit. Figure 2 As described, each of the pixel circuits may include a source synchronous transistor and a gate synchronous transistor. In another exemplary embodiment, as shown in FIG. Figure 4 As described, each of the pixel circuits may include a source synchronous transistor, a gate synchronous transistor, and a constant voltage synchronous transistor. In another exemplary embodiment, as shown in FIG. Figure 5 As described, each of the pixel circuits may include a source synchronous transistor, a gate synchronous transistor, a first constant voltage synchronous transistor, and a second constant voltage synchronous transistor. In another exemplary embodiment, as shown in FIG. Figure 6 As described, each of the pixel circuits may include a source synchronous transistor and a constant voltage synchronous transistor. In another exemplary embodiment, as shown in FIG. Figure 7 As described, each of the pixel circuits may include a source synchronous transistor, a first constant voltage synchronous transistor, and a second constant voltage synchronous transistor. In another exemplary embodiment, as shown in FIG. Figure 8 As described, each of the pixel circuits may include a gate synchronous transistor and a constant voltage synchronous transistor. In another exemplary embodiment, as shown in FIG. Fig. 9 As described, each of the pixel circuits may include a gate synchronous transistor, a first constant voltage synchronous transistor, and a second constant voltage synchronous transistor. Since the embodiments are described above, repeated descriptions related thereto will not be repeated.

[0089] The inventive concept can be applied to an organic light-emitting display device and an electronic device including the organic light-emitting display device. For example, the inventive concept can be applied to a cellular phone, a smart phone, a video phone, a smart tablet, a smart watch, a tablet PC, a car navigation system, a television, a computer monitor, a laptop computer, a head-mounted display device, an MP3 player, etc.

[0090] The pixel circuit according to the inventive concept may selectively shift the threshold voltage of the driving transistor according to the operation stage and / or operation condition of the organic light emitting display device by including at least two selected from the group consisting of a source synchronous transistor, a gate synchronous transistor, and a constant voltage synchronous transistor (for example, the threshold voltage of the driving transistor may be shifted in a first direction under a first operation condition (or in a first operation stage) to reduce (or improve) the instantaneous afterimage of the organic light emitting display device; the threshold voltage of the driving transistor may be shifted in a second direction opposite to the first direction under a second operation condition (or in a second operation stage) to increase (or improve) the instantaneous afterimage of the organic light emitting display device; The emission brightness of the light-emitting display device; and the threshold voltage of the driving transistor can be not shifted under the third operating condition (or in the third operating stage), the source synchronous transistor is electrically connected between the source electrode of the driving transistor and the bottom metal electrode of the driving transistor and is turned on or off in response to the source synchronization control signal, the gate synchronous transistor is electrically connected between the gate electrode of the driving transistor and the bottom metal electrode of the driving transistor and is turned on or off in response to the gate synchronization control signal, and the constant voltage synchronous transistor is electrically connected between the bottom metal electrode of the driving control transistor and the constant voltage supply line and is turned on or off in response to the constant voltage synchronization control signal.

[0091] Although specific exemplary embodiments have been described herein, other embodiments and modifications will be apparent from this description. Therefore, the inventive concept is not limited to such embodiments, but is limited to the broader scope of the appended claims and various obvious modifications and equivalent arrangements as will be apparent to those of ordinary skill in the art.

Claims

1. A pixel circuit, the pixel circuit include: Organic light emitting element; a switching transistor configured to be turned on or off in response to a scanning signal; a storage capacitor configured to store a data signal applied via a data line when the switching transistor is turned on in response to the scan signal; a driving transistor configured to allow a driving current corresponding to the data signal stored in the storage capacitor to flow into the organic light emitting element; an emission control transistor electrically connected in series to the organic light emitting element and the driving transistor between a high power supply voltage and a low power supply voltage and configured to be turned on or off in response to an emission control signal; as well as A plurality of synchronous transistors, connected directly to the bottom metal electrode of the driving transistor, in: The plurality of synchronous transistors include: a first synchronous transistor including a first electrode directly connected to a source electrode of the driving transistor, a second electrode directly connected to the bottom metal electrode of the driving transistor, and a gate electrode to which a first synchronous control signal is applied; and The second synchronous transistor includes a first electrode directly connected to the gate electrode of the driving transistor, a second electrode directly connected to the bottom metal electrode of the driving transistor, and a gate electrode to which a second synchronous control signal different from the first synchronous control signal is applied.

2. The pixel circuit according to claim 1, in: When the first synchronous transistor is turned on, the second synchronous transistor is turned off; and When the second synchronous transistor is turned on, the first synchronous transistor is turned off.

3. A pixel circuit, the pixel circuit include: Organic light emitting element; a switching transistor configured to be turned on or off in response to a scanning signal; a storage capacitor configured to store a data signal applied via a data line when the switching transistor is turned on in response to the scan signal; a driving transistor configured to allow a driving current corresponding to the data signal stored in the storage capacitor to flow into the organic light emitting element; an emission control transistor electrically connected in series to the organic light emitting element and the driving transistor between a high power supply voltage and a low power supply voltage and configured to be turned on or off in response to an emission control signal; a source synchronous transistor electrically connected between the source electrode of the driving transistor and the bottom metal electrode of the driving transistor and configured to be turned on or off in response to a source synchronous control signal; as well as The gate synchronous transistor is electrically connected between the gate electrode of the driving transistor and the bottom metal electrode of the driving transistor without passing through other transistors, and is configured to be turned on or off in response to a gate synchronous control signal.

4. The pixel circuit according to claim 3, in: The driving transistor is a p-channel metal oxide semiconductor transistor, and When the source synchronous transistor is turned on in response to the source synchronous control signal, the threshold voltage of the driving transistor shifts in a negative direction.

5. The pixel circuit according to claim 4, in: activating the source synchronization control signal during a first period during which the driving current flowing into the organic light emitting element needs to be reduced; and The source synchronous transistor is turned on during the first period to allow a source voltage of the source electrode of the drive transistor to be applied to the bottom metal electrode of the drive transistor.

6. The pixel circuit according to claim 3, in: The driving transistor is a p-channel metal oxide semiconductor transistor; and When the gate synchronous transistor is turned on in response to the gate synchronous control signal, a threshold voltage of the driving transistor shifts in a positive direction.

7. The pixel circuit according to claim 6, in: activating the gate synchronization control signal during a second period when the driving current flowing into the organic light emitting element needs to be increased; and The gate synchronous transistor is turned on during the second period to allow a gate voltage of the gate electrode of the driving transistor to be applied to the bottom metal electrode of the driving transistor.

8. The pixel circuit according to claim 3, wherein the pixel circuit further comprises: include: A constant voltage synchronous transistor is electrically connected between the bottom metal electrode of the driving transistor and a constant voltage supply line and is configured to be turned on or off in response to a constant voltage synchronous control signal.

9. The pixel circuit according to claim 8, in: The driving transistor is a p-channel metal oxide semiconductor transistor; The constant voltage supplied via the constant voltage supply line has a positive voltage level; and When the constant voltage synchronous transistor is turned on in response to the constant voltage synchronous control signal, the threshold voltage of the driving transistor shifts in a negative direction.

10. The pixel circuit according to claim 9, in, The constant voltage is the high power supply voltage.

11. The pixel circuit according to claim 9, in: activating the constant voltage synchronization control signal during a third period when the driving current flowing into the organic light emitting element needs to be reduced; and The constant voltage synchronous transistor is turned on during the third period to allow the constant voltage to be applied to the bottom metal electrode of the driving transistor.

12. The pixel circuit according to claim 8, in: The driving transistor is a p-channel metal oxide semiconductor transistor; The constant voltage supplied via the constant voltage supply line has a negative voltage level; and When the constant-voltage synchronous transistor is turned on in response to the constant-voltage synchronous control signal, the threshold voltage of the driving transistor shifts in a positive direction.

13. The pixel circuit according to claim 12, in, The constant voltage is the low power supply voltage.

14. The pixel circuit according to claim 12, in: activating the constant voltage synchronization control signal during a fourth period when the driving current flowing into the organic light emitting element needs to be increased; and The constant voltage synchronous transistor is turned on during the fourth period to allow the constant voltage to be applied to the bottom metal electrode of the driving transistor.

15. A pixel circuit, the pixel circuit include: Organic light emitting element; a switching transistor configured to be turned on or off in response to a scanning signal; a storage capacitor configured to store a data signal applied via a data line when the switching transistor is turned on in response to the scan signal; a driving transistor configured to allow a driving current corresponding to the data signal stored in the storage capacitor to flow into the organic light emitting element; an emission control transistor electrically connected in series to the organic light emitting element and the driving transistor between a high power supply voltage and a low power supply voltage and configured to be turned on or off in response to an emission control signal; a source synchronous transistor electrically connected between the source electrode of the driving transistor and the bottom metal electrode of the driving transistor and configured to be turned on or off in response to a source synchronous control signal; as well as A constant voltage synchronous transistor is electrically connected between the bottom metal electrode of the driving transistor and a constant voltage supply line and is configured to be turned on or off in response to a constant voltage synchronous control signal.

16. The pixel circuit according to claim 15, in: The driving transistor is a p-channel metal oxide semiconductor transistor; and When the source synchronous transistor is turned on in response to the source synchronous control signal, the threshold voltage of the driving transistor shifts in a negative direction.

17. The pixel circuit according to claim 15, in: The driving transistor is a p-channel metal oxide semiconductor transistor; and When the constant voltage synchronous transistor is turned on in response to the constant voltage synchronous control signal, the threshold voltage of the driving transistor shifts in a positive direction or in a negative direction.

18. A pixel circuit, the pixel circuit include: Organic light emitting element; a switching transistor configured to be turned on or off in response to a scanning signal; a storage capacitor configured to store a data signal applied via a data line when the switching transistor is turned on in response to the scan signal; a driving transistor configured to allow a driving current corresponding to the data signal stored in the storage capacitor to flow into the organic light emitting element; an emission control transistor electrically connected in series to the organic light emitting element and the driving transistor between a high power supply voltage and a low power supply voltage and configured to be turned on or off in response to an emission control signal; a gate synchronous transistor electrically connected between the gate electrode of the driving transistor and the bottom metal electrode of the driving transistor and configured to be turned on or off in response to a gate synchronous control signal; as well as A constant voltage synchronous transistor is electrically connected between the bottom metal electrode of the driving transistor and a constant voltage supply line and is configured to be turned on or off in response to a constant voltage synchronous control signal.

19. The pixel circuit according to claim 18, in: The driving transistor is a p-channel metal oxide semiconductor transistor; and When the gate synchronous transistor is turned on in response to the gate synchronous control signal, a threshold voltage of the driving transistor shifts in a positive direction.

20. The pixel circuit according to claim 18, in: The driving transistor is a p-channel metal oxide semiconductor transistor; and When the constant voltage synchronous transistor is turned on in response to the constant voltage synchronous control signal, the threshold voltage of the driving transistor shifts in a positive direction or in a negative direction.

Images