Organic light-emitting diode display device including compensation unit and driving method thereof

Abstract

An organic light-emitting diode (OLED) display device including a compensation unit and a driving method thereof are disclosed. The OLED display device includes: a driving transistor; a first transistor, which is switched according to an nth gate voltage and connected to a data voltage and the driving transistor; a second transistor, which is switched according to an nth initialization voltage and connected to an initial voltage and the driving transistor; a third transistor, which is switched according to an nth sensed voltage and connected to a reference voltage and the driving transistor; a fourth transistor, which is switched according to an (n-2)th sensed voltage and connected to the initial voltage and the driving transistor; a storage capacitor connected to the driving transistor and the first transistor; and a light-emitting diode connected to a low-level voltage and the driving transistor.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2021-0193085, filed on December 30, 2021, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This invention relates to an organic light-emitting diode (OLED) display device, and more specifically, to an OLED display device including a compensation unit and a method for driving the OLED display device, wherein by sequentially driving two transistors connected to the source of a driving transistor, kickback amount of low-level voltage is reduced and degradation such as crosstalk is prevented. Background Technology

[0004] Recently, with the advent of the information society, the increasing attention paid to information displays for processing and displaying large amounts of information, and the growing demand for portable information media, the display field has experienced rapid development. Consequently, various thin and light flat panel display devices have been developed and have become a highlight.

[0005] Among various flat panel display devices, organic light-emitting diode (OLED) displays are light-emitting devices and do not include the backlight unit used in non-light-emitting devices such as liquid crystal displays (LCDs). As a result, OLED displays have advantages in viewing angle, contrast ratio, and power consumption, thus finding applications in a wide range of fields.

[0006] In OLED display devices, each sub-pixel includes a compensation unit with various structures for compensating the threshold voltage of the driving transistors. A 4T1C structure (where each sub-pixel includes four transistors and one capacitor) compensation unit was researched and developed.

[0007] In OLED display devices with compensation units featuring a 4T1C structure, image quality degradation is minimized by compensating for the threshold voltage. However, degradation such as horizontal crosstalk can occur because the source voltage of the driving transistor changes due to low-level voltage transitions during the initialization period. Summary of the Invention

[0008] Therefore, the present invention aims to provide an organic light-emitting diode (OLED) display device and a method for driving an OLED display device, which substantially solves one or more problems caused by the limitations and defects of related technologies.

[0009] One object of the present invention is to provide an organic light-emitting diode display device including a compensation unit and a method for driving the organic light-emitting diode display device, wherein the source voltage of the driving transistor is changed from an initial value to a final value via a median value by two transistors that are sequentially switched during an initialization period and connected to the source of the driving transistor, thereby minimizing the jump variable of the low-level voltage and preventing degradation such as horizontal crosstalk.

[0010] Another object of the present invention is to provide an organic light-emitting diode display device including a compensation unit, wherein by using an initial voltage applied to the gate of the driving transistor as an intermediate value of the source voltage of the driving transistor and using the same type of gate signal to drive two transistors connected to the source of the driving transistor, the structure of the power supply unit and the gate driving unit is simplified, degradation such as horizontal crosstalk is prevented, and the display quality is improved.

[0011] Additional features and advantages of the invention will be set forth in the description which follows, will be apparent in part from the description, or may be learned by practice of the invention. These and other advantages of the invention will be realized and obtained by means of the structures specifically pointed out in the written description, the claims, and the drawings.

[0012] To achieve these and other advantages and in accordance with the intent of the invention, as embodied and broadly described herein, an organic light-emitting diode (OLED) display device includes: a driving transistor; a first transistor, which is switched according to an nth gate voltage and connected to a data voltage and the driving transistor; a second transistor, which is switched according to an nth initialization voltage and connected to an initial voltage and the driving transistor; a third transistor, which is switched according to an nth sensed voltage and connected to a reference voltage and the driving transistor; a fourth transistor, which is switched according to an (n-2)th sensed voltage and connected to the initial voltage and the driving transistor; a storage capacitor connected to the driving transistor and the first transistor; and a light-emitting diode connected to a low-level voltage and the driving transistor.

[0013] In another aspect, a method for driving an organic light-emitting diode (OLED) display device is provided. The OLED display device includes a driving transistor, a first transistor, a second transistor, a third transistor, a fourth transistor, a storage capacitor, and an OLED. The method includes: during a first time period, turning off the first transistor, the second transistor, and the third transistor, turning on the fourth transistor, and providing an initial voltage to the source of the driving transistor; during a second time period, turning off the first transistor and the fourth transistor, turning on the second transistor and the third transistor, and providing a reference voltage and the initial voltage to the source and gate of the driving transistor, respectively; during a third time period, turning off the first transistor, the third transistor, and the fourth transistor, turning on the second transistor, and providing the initial voltage to the gate of the driving transistor; and during a fourth time period, turning on the first transistor, turning off the second transistor, the third transistor, and the fourth transistor, and providing a data voltage to the gate of the driving transistor.

[0014] It will be understood that the foregoing general description and the following detailed description are illustrative and intended to provide further explanation of the claimed invention. Attached Figure Description

[0015] The accompanying drawings, which provide a further understanding of the invention and are incorporated in and form a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:

[0016] Figure 1 This is a view showing an organic light-emitting diode display device according to a first embodiment of the present invention;

[0017] Figure 2 This is a circuit diagram showing a sub-pixel of an organic light-emitting diode display device according to an embodiment of the present invention;

[0018] Figure 3 This is a view showing multiple signals used in a sub-pixel of an organic light-emitting diode display device according to an embodiment of the present invention;

[0019] Figure 4A This is a view showing the second node voltage of a sub-pixel of an organic light-emitting diode display device according to an embodiment of the present invention;

[0020] Figure 4B This is a view showing the low-level voltage of an organic light-emitting diode display device according to an embodiment of the present invention;

[0021] Figure 5 This is a graph showing the jump variables of an organic light-emitting diode display device according to an embodiment of the present invention. Detailed Implementation

[0022] The advantages and features of the present invention, as well as its implementation methods, will become apparent from the exemplary embodiments described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in various forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete, enabling those skilled in the art to fully understand the scope of the invention. Furthermore, the invention is defined only by the scope of the claims.

[0023] The shapes, dimensions, proportions, angles, and quantities disclosed in the drawings for the purpose of describing embodiments of the invention are merely exemplary. Therefore, the invention is not limited to the details illustrated. Similar reference numerals refer to similar elements throughout the application. In the following description, detailed descriptions of known functions or constructions may be omitted when it is determined that such detailed descriptions would unnecessarily obscure the focus of the invention. Where the terms "comprising," "having," and "including" are used in the description herein, additional terms may be added unless more restrictive terms such as "only" are used.

[0024] When interpreting an element, even if there is no explicit description of the error or tolerance range, the element should be interpreted as including such an error or tolerance range.

[0025] When describing positional relationships, for example, when the positional relationship between two parts is described as "on," "above," "below," or "next to," one or more additional parts may be placed between the two parts, unless more restrictive terms such as "exactly" or "directly" are used.

[0026] It will be understood that although terms such as "first," "second," etc., are used to describe various elements, these elements should not be limited by these terms. These terms are merely used to distinguish one element from another. Therefore, without departing from the scope of the invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0027] The features of the various embodiments of the present invention can be combined or integrated with each other, either partially or entirely, and can be interoperable and driven in various ways, as will be fully understood by those skilled in the art. The embodiments of the present invention can be implemented independently of each other or together in an associated relationship.

[0028] Hereinafter, an organic light-emitting diode display device including a compensation unit according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Throughout the description, the same reference numerals refer to the same elements. Detailed descriptions of well-known functions or structures relevant to this document will be omitted or will be provided briefly when it is determined that such detailed descriptions would unnecessarily obscure the essential points of the inventive concept.

[0029] Figure 1 This is a view showing an organic light-emitting diode display device according to a first embodiment of the present invention.

[0030] exist Figure 1 In this invention, an organic light-emitting diode (OLED) display device 110 includes a timing control unit 120, a data driving unit 130, a gate driving unit 140, and a display panel 150.

[0031] The timing control unit 120 uses image signals transmitted from an external system, such as a graphics card or television system, and multiple timing signals, including a data enable signal, a horizontal synchronization signal, a vertical synchronization signal, and a clock signal, to generate image data, data control signals, and gate control signals. The image data and data control signals are transmitted to the data drive unit 130, and the gate control signals are transmitted to the gate drive unit 140.

[0032] The data drive unit 130 uses data control signals and image data transmitted from the timing control unit 120 to generate a data voltage (data signal) and transmits the data voltage to the data line DL of the display panel 150.

[0033] The gate driving unit 140 uses the gate control signal transmitted from the timing control unit 120 to generate a gate voltage (gate signal), an initialization voltage (initialization signal), and a sensing voltage (sensing signal), and applies the gate voltage, initialization voltage, and sensing voltage to the gate line GL, initialization line, and sensing line of the display panel 150, respectively.

[0034] The gate driving unit 140 may have an in-panel gate (GIP) type, which is formed in the non-display area NDA of the substrate of the display panel 150 having gate lines GL, data lines DL and pixels P.

[0035] Display panel 150 includes a display area DA in its central portion and a non-display area NDA surrounding the display area DA. Display panel 150 displays images using gate voltage, initialization voltage, sensing voltage, and data voltage. To display images, display panel 150 includes multiple pixels P, multiple gate lines GL, multiple initialization lines, multiple sensing lines, and multiple data lines DL in the display area DA.

[0036] Multiple initialization lines and multiple sensing lines can be separated from and spaced apart from multiple gate lines GL.

[0037] For example, each of the plurality of pixels P may include a red sub-pixel SPr, a green sub-pixel SPg, and a blue sub-pixel SPb, and gate line GL and data line DL intersect each other to define the red sub-pixel SPr, the green sub-pixel SPg, and the blue sub-pixel SPb. Each of the red sub-pixel SPr, the green sub-pixel SPg, and the blue sub-pixel SPb may be connected to gate line GL and data line DL.

[0038] The structure and operation of each subpixel of the display panel 150 of the OLED display device 110 will be illustrated with reference to the accompanying drawings.

[0039] Figure 2 This is a circuit diagram showing a sub-pixel of an organic light-emitting diode display device according to an embodiment of the present invention; Figure 3 This is a view illustrating multiple signals used in a sub-pixel of an organic light-emitting diode display device according to an embodiment of the present invention.

[0040] exist Figure 2 In the OLED display device 110 according to an embodiment of the present invention, each of the red sub-pixel SPr, green sub-pixel SPg and blue sub-pixel SPb of the display panel 150 includes a driving transistor Td, first to fourth transistors T1 to T4, a storage capacitor CST and a light-emitting diode De.

[0041] For example, the driving transistor Td and the first to fourth transistors T1 to T4 can be negative polycrystalline silicon thin-film transistors or negative oxide semiconductor thin-film transistors.

[0042] The driving transistor Td is switched (on / off) according to the voltage of the first electrode of the storage capacitor CST. The gate of the driving transistor Td is connected to the first electrode of the storage capacitor CST, the source of the first transistor T1 and the source of the second transistor T2, the drain of the driving transistor Td is connected to the high-level voltage Vdd, and the source of the driving transistor Td, which serves as the second node n2, is connected to the second electrode of the storage capacitor CST, the source of the third transistor T3, the source of the fourth transistor T4, and the anode of the light-emitting diode De.

[0043] The first transistor T1, acting as a switching transistor, is switched (on / off) according to the nth gate voltage SCAN(n), where n is a positive integer greater than 2. The gate of the first transistor T1 is connected to the nth gate voltage SCAN(n), the drain of the first transistor T1 is connected to the data voltage Vdata, and the source of the first transistor T1 is connected to the gate of the driving transistor Td, the first electrode of the storage capacitor CST, and the source of the second transistor T2.

[0044] The second transistor T2, acting as an initialization transistor, is switched (on / off) according to the nth initialization voltage INIT(n). The gate of the second transistor T2 is connected to the nth initialization voltage INIT(n), the drain of the second transistor T2 is connected to the initial voltage Vini, and the source of the second transistor T2 is connected to the gate of the driving transistor Td, the first electrode of the storage capacitor CST, and the source of the first transistor T1.

[0045] The third transistor T3, acting as a sensing transistor, is switched (on / off) according to the nth sensing voltage SENS(n). The gate of the third transistor T3 is connected to the nth sensing voltage SENS(n), the drain of the third transistor T3 is connected to the reference voltage Vref, and the source of the third transistor T3 is connected to the source of the driving transistor Td, the second electrode of the storage capacitor CST, and the source of the fourth transistor T4.

[0046] The fourth transistor T4, acting as a sensing transistor, is switched (on / off) according to the (n-2)th sensing voltage SENS(n-2). The gate of the fourth transistor T4 is connected to the (n-2)th sensing voltage SENS(n-2), the drain of the fourth transistor T4 is connected to the initial voltage Vini, and the source of the fourth transistor T4 is connected to the source of the driving transistor Td, the second electrode of the storage capacitor CST, the source of the third transistor T3, and the anode of the light-emitting diode De.

[0047] The storage capacitor CST stores the threshold voltage Vth. The first electrode of the storage capacitor CST is connected to the gate of the driving transistor Td, the source of the first transistor T1, and the source of the second transistor T2. The second electrode of the storage capacitor CST is connected to the source of the driving transistor Td, the source of the third transistor T3, the source of the fourth transistor T4, and the anode of the light-emitting diode De.

[0048] The light-emitting diode De is connected between the driving transistor Td and the low-level voltage Vss, and emits light with a brightness proportional to the current of the driving transistor Td. The anode of the light-emitting diode De is connected to the source of the driving transistor Td, the second electrode of the storage capacitor CST, the source of the third transistor T3, and the source of the fourth transistor T4, and the cathode of the light-emitting diode De is connected to the low-level voltage Vss.

[0049] The gate of the driving transistor Td, the first electrode of the storage capacitor CST, the source of the first transistor T1 and the source of the second transistor T2 are connected to each other to form a first node n1, and the source of the driving transistor Td, the second electrode of the storage capacitor CST, the source of the third transistor T3 and the source of the fourth transistor T4 are connected to each other to form a second node n2.

[0050] The initial voltage Vini can be higher than the reference voltage Vref.

[0051] The (n-2)th sensing voltage SENS(n-2) can be the voltage used in the (n-2)th horizontal pixel row, which is two rows earlier than the nth horizontal pixel row using the nth sensing voltage SENS(n).

[0052] exist Figure 3 In the OLED display device 110 according to an embodiment of the present invention, each sub-pixel SP emits light in units of frames, and a frame, as the smallest unit, includes first to sixth time periods TP1 to TP6.

[0053] During the first time period TP1 of the initialization phase, the nth initialization voltage INIT(n), the nth sense voltage SENS(n), and the nth gate voltage SCAN(n) become low logic voltage Vl, and the (n-2)th sense voltage SENS(n-2) becomes high logic voltage Vh. The first transistor T1, the second transistor T2, and the third transistor T3 are turned off, and the fourth transistor T4 is turned on. As a result, the second node voltage Vn2 of the second node n2 becomes the initial voltage Vini, thereby driving the source of transistor Td to be initially initialized.

[0054] For example, the first time period TP1 can correspond to approximately 1.5 horizontal cycles (1.5H).

[0055] During the second time period TP2 of the initialization phase, the nth initialization voltage INIT(n) and the nth sense voltage SENS(n) become high logic voltage Vh, and the (n-2)th sense voltage SENS(n-2) and the nth gate voltage SCAN(n) become low logic voltage Vl. The first transistor T1 and the fourth transistor T4 are turned off, and the second transistor T2 and the third transistor T3 are turned on. As a result, the first node voltage Vn1 of the first node n1 becomes the initial voltage Vini, thereby driving the gate of transistor Td to be initialized, and the second node voltage Vn2 of the second node n2 becomes the reference voltage Vref, thereby driving the source of transistor Td to be re-initialized.

[0056] For example, the second time period TP2 can correspond to approximately 1.5 horizontal cycles (1.5H).

[0057] During the third time period TP3, which is the sensing period, the nth initialization voltage INIT(n) becomes a high logic voltage Vh, and the nth sensing voltage SENS(n), the (n-2)th sensing voltage SENS(n-2), and the nth gate voltage SCAN(n) become low logic voltages Vl. The first transistor T1, the third transistor T3, and the fourth transistor T4 are turned off, and the second transistor T2 is turned on. As a result, the first node voltage Vn1 of the first node n1 remains at the initial voltage Vini, and the second node voltage Vn2 of the second node n2 becomes the value obtained by subtracting the threshold voltage Vth of the driving transistor Td from the initial voltage Vini (Vini-Vth), thereby storing the threshold voltage Vth in the storage capacitor CST.

[0058] For example, the third time period TP3 can be approximately 200 μs.

[0059] During the fourth time period TP4, which is the write phase, the nth initialization voltage INIT(n), the nth sensing voltage SENS(n), and the (n-2)th sensing voltage SENS(n-2) become low logic voltages Vl, and the nth gate voltage SCAN(n) becomes high logic voltage Vh. The first transistor T1 is turned on, and the second transistor T2, the third transistor T3, and the fourth transistor T4 are turned off. As a result, the first node voltage Vn1 of the first node n1 becomes the value obtained by adding the data voltage Vdata to the initial voltage Vini (Vini+Vdata), and the second node voltage Vn2 of the second node n2 remains at the value obtained by subtracting the threshold voltage Vth of the driving transistor Td from the initial voltage Vini (Vini-Vth), thereby writing the data voltage Vdata to the gate of the driving transistor Td.

[0060] During the period between the third time period TP3 and the fourth time period TP4, the first transistor T1, the second transistor T2, the third transistor T3, and the fourth transistor T4 are turned off, and the gate and source of the driving transistor Td are electrically floated. For example, the period between the third time period TP3 and the fourth time period TP4 may correspond to approximately 0.7 horizontal cycles (0.7H).

[0061] During the fifth time period TP5, which is the boosting period, the nth initialization voltage INIT(n), the nth sensing voltage SENS(n), the (n-2)th sensing voltage SENS(n-2), and the nth gate voltage SCAN(n) become low logic voltage V1. The first transistor T1, the second transistor T2, the third transistor T3, and the fourth transistor T4 are turned off. As a result, the first node voltage Vn1 of the first node n1 gradually increases via the storage capacitor CST, becoming the value obtained by adding the boost voltage Vboo to the sum of the initial voltage Vini and the data voltage Vdata (Vini+Vdata+Vboo), and the second node voltage Vn2 of the second node n2 gradually increases via the turned-on drive transistor Td, becoming the value obtained by adding the boost voltage Vboo to the difference between the initial voltage Vini and the threshold voltage Vth (Vini-Vth+Vboo), thereby charging the anode of the light-emitting diode De. In other words, during the fifth time period TP5, a high-level voltage is provided to the light-emitting diode De to increase the voltage at the anode of the light-emitting diode De.

[0062] During the sixth time period TP6, which is the light-emitting period, the nth initialization voltage INIT(n), the nth sensing voltage SENS(n), the (n-2)th sensing voltage SENS(n-2), and the nth gate voltage SCAN(n) become low logic voltage V1. The first transistor T1, the second transistor T2, the third transistor T3, and the fourth transistor T4 are turned off. As a result, a current proportional to the square of the value (Vdata) obtained by subtracting the threshold voltage Vth from the gate-source voltage (Vgs = (Vg-Vs) = (Vini + Vdata + Vboo) - (Vini - Vth + Vboo) = Vdata + Vth) flows through the driving transistor Td, and the second node voltage Vn2 of the second node n2 becomes higher than the threshold voltage of the light-emitting diode De, thereby causing the light-emitting diode De to emit light with a brightness corresponding to the current flowing through the driving transistor Td. In other words, during the sixth time period TP6, a high-level voltage is provided to the light-emitting diode De to make it emit light.

[0063] Before the first time period TP1, the second node voltage Vn2 of the second node n2 remains at the previous voltage Vpre, which corresponds to the data voltage Vdata of the previous frame. Furthermore, the second node voltage Vn2 of the second node n2 changes to the initial voltage Vini during the first time period TP1, and changes to the reference voltage Vref during the second time period TP2.

[0064] For example, the previous voltage Vpre may be higher than the initial voltage Vini and the reference voltage Vref, and the initial voltage Vini may be lower than the previous voltage Vpre and higher than the reference voltage Vref. The initial voltage Vini may have a value between the previous voltage Vpre and the reference voltage Vref.

[0065] Since the light-emitting diode De is equivalent to the light-emitting capacitor Ce, the low-level voltage Vss changes according to the change of the second node voltage Vn2 of the second node n2. As a result, the first transition KB1 of the low-level voltage Vss occurs at the start time of the first time period TP1 corresponding to the change time of the second node voltage Vn2, and the second transition KB2 of the low-level voltage Vss occurs at the start time of the second time period TP2 corresponding to the change time of the second node voltage Vn2.

[0066] The voltage drop of the low-level voltage Vss is caused by the first transition KB1 and the second transition KB2, and can be expressed by the following equation:

[0067] V(KB1)=(Ce / Ce+Cst)*(Vpre-Vini);

[0068] V(KB2)=(Ce / Ce+Cst)*(Vini-Vref).

[0069] During the sensing period of each sub-pixel SP in the previous horizontal pixel row, the voltage drop of the low-level voltage Vss causes the second node voltage Vn2 to decrease due to coupling via the light-emitting capacitor Ce. As a result, the gate-source voltage Vgs increases, and the brightness of the light emitted from the light-emitting diode De increases, leading to degradations such as crosstalk.

[0070] When the second node voltage Vn2 drops directly from the previous voltage Vpre to the reference voltage Vref in one step, the voltage drop of the low-level voltage Vss caused by the transition can be expressed by the following equation:

[0071] V(KB)=(Ce / Ce+Cst)*(Vpre-Vref).

[0072] In the OLED display device 110 according to an embodiment of the present invention, the second node voltage Vn2 first decreases from the previous voltage Vpre to the initial voltage Vini as an intermediate value, and then decreases from the initial voltage Vini to the reference voltage Vref as a final value. As a result, the voltage drop amounts of the first transition KB1 and the second transition KB2 are reduced compared to the voltage drop amount of the transition KB (V(KB1) < V(KB), V(KB2) < V(KB)). In addition, the decrease in the second node voltage Vn2 of each subpixel SP in a previous horizontal pixel row and the increase in the gate-source voltage Vgs are minimized, preventing degradation such as crosstalk.

[0073] The voltage drop amounts of the transitions will be illustrated with reference to the drawings.

[0074] Figure 4A is a view showing the second node voltage of a subpixel of an organic light emitting diode display device according to an embodiment of the present invention; Figure 4B is a view showing the low-level voltage of an organic light emitting diode display device according to an embodiment of the present invention; Figure 5 is a graph showing the transition amounts of an organic light emitting diode display device according to an embodiment of the present invention.

[0075] In accordance with Figure 4A In the OLED display device of the comparative example, the second node voltage Vn2 directly decreases from the previous voltage Vpre to the reference voltage Vref at the rising time of the n-th sense voltage SENS(n).

[0076] In Figure 4A In the OLED display device 100 according to an embodiment of the present invention, the second node voltage Vn2 decreases from the previous voltage Vpre to the initial voltage Vini as an intermediate value at the rising time of the (n - 2)-th sense voltage SENS(n - 2), and the second node voltage Vn2 decreases from the initial voltage Vini to the reference voltage Vref at the rising time of the n-th sense voltage SENS(n).

[0077] In the OLED display device 110 according to an embodiment of the present invention, the second node voltage Vn2 decreases from the previous voltage Vre to the reference voltage Vref as a final value sequentially and in sections via the intermediate initial voltage.

[0078] In Figure 4B In the OLED display device 110 according to an embodiment of the present invention, the voltage drop amount of the second transition KB2 of the low-level voltage Vss is less than the voltage drop amount of the transition KB of the low-level voltage Vss of the OLED display device according to the comparative example.

[0079] For example, in Figure 5In the example, when the reference value Vsr of the low-level voltage Vss is approximately 3V, the peak value Vkp of the low-level voltage Vss of the comparative example switch KB can be approximately 2.8802V, and the peak jump value (Vsr-Vkp) of the voltage drop of the low-level voltage Vss of the comparative example switch KB can be approximately 0.1198V. Furthermore, when the reference value Vsr of the low-level voltage Vss is approximately 3V, the peak value Vkp of the low-level voltage Vss of the second switch KB2 in the embodiment can be approximately 2.9934V, and the peak jump value (Vsr-Vkp) of the voltage drop of the low-level voltage Vss of the second switch KB2 in the embodiment can be approximately 0.0666V.

[0080] Compared to the peak jump variable (Vsr-Vkp) of the comparative example, the peak jump variable (Vsr-Vkp) of the embodiment of the present invention is reduced by approximately 44%.

[0081] When the reference value Vsr of the low-level voltage Vss is approximately 3V, the recovery value Vkr of the low-level voltage Vss after one horizontal cycle (1H) of the transition KB in the comparative example can be approximately 2.9685V, and the recovery jump amount (Vsr-Vkr) of the voltage drop of the low-level voltage Vss after one horizontal cycle (1H) of the transition KB in the comparative example can be approximately 0.0315V. Furthermore, when the reference value Vsr of the low-level voltage Vss is approximately 3V, the recovery value Vkr of the low-level voltage Vss after one horizontal cycle (1H) of the second transition KB2 in the embodiment can be approximately 2.9759V, and the recovery jump amount (Vsr-Vkr) of the voltage drop of the low-level voltage Vss after one horizontal cycle (1H) of the second transition KB2 in the embodiment can be approximately 0.0241V.

[0082] Since the recovery jump variable (Vsr-Vkr) of the embodiment of the present invention is reduced by about 23% compared with the recovery jump variable (Vsr-Vkr) of the comparative example, the recovery time of the low-level voltage Vss of the embodiment of the present invention is reduced compared with the recovery time of the low-level voltage Vss of the comparative example.

[0083] In addition, the first transition KB1 may have a low-level voltage Vss with a peak value Vkp, a peak transition variable (Vsr-Vkp), a recovery value Vkr, and a recovery transition variable (Vsr-Vkr) similar to the second transition KB2.

[0084] Therefore, in the OLED display device 110 according to an embodiment of the present invention, the source voltage of the driving transistor Td changes from a previous voltage Vpre, which is a starting value, to an initial voltage Vini, which is an intermediate value, during a first time period TP1, which is a first initialization period, and changes from the initial voltage Vini, which is an intermediate value, to a reference voltage Vref, which is a final value, during a second time period TP2, which is a second initialization period TP2. As a result, the peak jump variable (Vsr-Vkp) and the recovery jump variable (Vsr-Vkr) of the first jump KB1 and the second jump KB2 are minimized, and the decrease of the second node voltage Vn2 of each sub-pixel SP of the previous horizontal pixel row and the increase of the gate-source voltage Vgs are minimized. Therefore, degradation such as crosstalk is prevented.

[0085] Furthermore, the initial voltage Vini used to initialize the gate of the driving transistor Td is applied to the source of the driving transistor Td via the fourth transistor T4 as an intermediate value for the second node voltage Vn2. As a result, an increase in the required source voltage is prevented, simplifying the power supply unit.

[0086] Furthermore, since the third transistor T3 and the fourth transistor T4, which are connected to the source of the driving transistor Td, switch according to the nth sense voltage SENS(n) and the (n-2)th sense voltage SENS(n-2) of the same kind, the increase in the number of required gate signals is prevented, and the gate driving unit 140 is simplified.

[0087] Various modifications and variations may be made to this invention without departing from its scope, as will be apparent to those skilled in the art. Therefore, this invention is intended to cover any modifications and variations that fall within the scope of the appended claims and their equivalents.

Claims

1. An organic light-emitting diode (OLED) display device, comprising: Drive transistors; A first transistor, which is switched according to an nth gate voltage and connected to a data voltage and the driving transistor, wherein n is a positive integer greater than 2; The second transistor switches according to the nth initialization voltage and is connected to the initial voltage and the driving transistor; A third transistor, which switches according to the nth sensed voltage and is connected to a reference voltage and the driving transistor; A fourth transistor, which switches according to the (n-2)th sensed voltage and is connected to the initial voltage and the driving transistor; A storage capacitor connected to the driving transistor and the first transistor; as well as The light-emitting diode connected to the low-level voltage and the driving transistor, The gate of the driving transistor is connected to the first electrode of the storage capacitor, the source of the first transistor, and the source of the second transistor; the drain of the driving transistor is connected to a high-level voltage; and the source of the driving transistor is connected to the second electrode of the storage capacitor, the source of the third transistor, the source of the fourth transistor, and the anode of the light-emitting diode. A single frame used to display an image includes a first time segment, a second time segment, a third time segment, and a fourth time segment. The source of the driving transistor had a previous voltage prior to the first time period. The source of the driving transistor has the initial voltage during the first time period. The source of the driving transistor has the reference voltage during the second time period. The initial voltage has a value between the previous voltage and the reference voltage.

2. The organic light-emitting diode display device according to claim 1, wherein the driving transistor, the first transistor, the second transistor, the third transistor, and the fourth transistor are one of a negative polycrystalline silicon thin-film transistor and a negative oxide semiconductor thin-film transistor.

3. The organic light-emitting diode display device according to claim 1, The gate of the first transistor is connected to the nth gate voltage, the drain of the first transistor is connected to the data voltage, and the source of the first transistor is connected to the gate of the driving transistor, the first electrode of the storage capacitor, and the source of the second transistor. The gate of the second transistor is connected to the nth initialization voltage, the drain of the second transistor is connected to the initial voltage, and the source of the second transistor is connected to the gate of the driving transistor, the first electrode of the storage capacitor, and the source of the first transistor. The gate of the third transistor is connected to the nth sensed voltage, the drain of the third transistor is connected to the reference voltage, and the source of the third transistor is connected to the source of the driving transistor, the second electrode of the storage capacitor, and the source of the fourth transistor. The gate of the fourth transistor is connected to the (n-2)th sense voltage, the drain of the fourth transistor is connected to the initial voltage, and the source of the fourth transistor is connected to the source of the driving transistor, the second electrode of the storage capacitor, the source of the third transistor, and the anode of the light-emitting diode. The first electrode of the storage capacitor is connected to the gate of the driving transistor, the source of the first transistor, and the source of the second transistor; the second electrode of the storage capacitor is connected to the source of the driving transistor, the source of the third transistor, the source of the fourth transistor, and the anode of the light-emitting diode. The anode of the light-emitting diode is connected to the source of the driving transistor, the second electrode of the storage capacitor, the source of the third transistor, and the source of the fourth transistor, and the cathode of the light-emitting diode is connected to the low-level voltage.

4. The organic light-emitting diode display device according to claim 1, During the first time period, the nth initialization voltage, the nth sensing voltage, and the nth gate voltage have low logic voltages, and the (n-2)th sensing voltage has a high logic voltage. During the second time period, the nth initialization voltage and the nth sense voltage have high logic voltages, and the (n-2)th sense voltage and the nth gate voltage have low logic voltages. During the third time period, the nth initialization voltage has a high logic voltage, and the nth sense voltage, the (n-2)th sense voltage, and the nth gate voltage have low logic voltages. During the fourth time period, the nth initialization voltage, the nth sensing voltage, and the (n-2)th sensing voltage have low logic voltages, and the nth gate voltage has a high logic voltage.

5. The organic light-emitting diode display device according to claim 4, wherein the frame further comprises a fifth time period and a sixth time period. During the fifth and sixth time periods, the nth initialization voltage, the nth sensing voltage, the (n-2)th sensing voltage, and the nth gate voltage have low logic voltages.

6. The organic light-emitting diode display device according to claim 5, wherein during the second time period, the gate of the driving transistor has the initial voltage, and the source of the driving transistor has the reference voltage. During the third time period, the gate of the driving transistor has the initial voltage, and the source of the driving transistor has a value obtained by subtracting the threshold voltage of the driving transistor from the initial voltage. During the fourth time period, the gate of the driving transistor has a value obtained by adding the data voltage to the initial voltage, and the source of the driving transistor has a value obtained by subtracting the threshold voltage from the initial voltage. During the fifth time period, the gate of the driving transistor has a value obtained by adding a boost voltage to the sum of the initial voltage and the data voltage, and the source of the driving transistor has a value obtained by adding the boost voltage to the difference between the initial voltage and the threshold voltage.

7. A method for driving an organic light-emitting diode (OLED) display device, the OLED display device comprising a driving transistor, a first transistor, a second transistor, a third transistor, a fourth transistor, a storage capacitor, and a light-emitting diode, the method comprising: During the first time period, the first transistor, the second transistor, and the third transistor are turned off, the fourth transistor is turned on, and an initial voltage is provided to the source of the driving transistor; During the second time period, the first transistor and the fourth transistor are turned off, the second transistor and the third transistor are turned on, and a reference voltage and the initial voltage are respectively provided to the source and gate of the driving transistor. During the third time period, the first transistor, the third transistor, and the fourth transistor are turned off, the second transistor is turned on, and the initial voltage is provided to the gate of the driving transistor; as well as During the fourth time period, the first transistor is turned on, while the second, third, and fourth transistors are turned off, and a data voltage is supplied to the gate of the driving transistor. The second transistor is switched according to the nth initialization voltage and is connected to the initial voltage and the driving transistor, where n is a positive integer greater than 2; The third transistor is switched according to the nth sensed voltage and is connected to the reference voltage and the driving transistor; The gate of the driving transistor is connected to the first electrode of the storage capacitor, the source of the first transistor, and the source of the second transistor; the drain of the driving transistor is connected to a high-level voltage; and the source of the driving transistor is connected to the second electrode of the storage capacitor, the source of the third transistor, the source of the fourth transistor, and the anode of the light-emitting diode.

8. The method according to claim 7, further comprising: During the fifth time period, the first transistor, the second transistor, the third transistor, and the fourth transistor are turned off, and a high-level voltage is provided to the light-emitting diode to increase the voltage at the anode of the light-emitting diode. During the sixth time period, the first transistor, the second transistor, the third transistor, and the fourth transistor are turned off, and the high-level voltage is provided to the light-emitting diode to make the light-emitting diode emit light.

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