Patent Application
20240312411
The present disclosure relates to, but is not limited to, the field of display technologies, and in particular to a pixel drive circuit, a method for driving the pixel drive circuit, and a display device.
An organic light emitting diode (OLED for short), a quantum dot light emitting diode (QLED for short), and a micro light emitting diode are active light emitting display devices and have advantages such as self-luminescence, wide viewing angle, high contrast ratio, low power consumption, very high response speed, lightness and thinness, flexibility, and low cost. With continuous development of display technologies, a flexible display device (Flexible Display) in which an OLED, QLED, or micro light emitting diode is used as a light emitting element and a Thin Film Transistor (TFT) is used for signal control has become a mainstream product in the field of display at present.
The following is a summary of subject matter described in the present disclosure in detail. This summary is not intended to limit the protection scope of claims.
In a first aspect, the present disclosure provides a pixel drive circuit, the pixel drive circuit is configured to drive a light emitting device to emit light, the light emitting device includes a first electrode and a second electrode, the pixel drive circuit includes a current control sub-circuit and a duration control sub-circuit;
In an exemplary implementation, the duration control sub-circuit includes a first node control sub-circuit, a first drive sub-circuit, a first output control sub-circuit, and a first storage sub-circuit;
In an exemplary implementation, the current control sub-circuit includes: a second node control sub-circuit, a second drive sub-circuit, a second output control sub-circuit, and a second storage sub-circuit;
In an exemplary implementation, a reset sub-circuit is further included;
In an exemplary implementation, the first node control sub-circuit includes: a first transistor, a second transistor, a fourth transistor, and a seventh transistor, the first drive sub-circuit includes: a third transistor, and the first output control sub-circuit includes: a fifth transistor and a sixth transistor;
In an exemplary implementation, the first storage sub-circuit includes: a first capacitor;
In an exemplary implementation, the second node control sub-circuit includes: an eighth transistor, a ninth transistor, and an eleventh transistor;
In an exemplary implementation, the second drive sub-circuit includes: a tenth transistor and the second output control sub-circuit includes: a twelfth transistor and a thirteenth transistor;
In an exemplary implementation, the second storage sub-circuit includes a second capacitor and a third capacitor;
In an exemplary implementation, the reset sub-circuit includes: a fourteenth transistor;
In an exemplary implementation, a reset sub-circuit is further included, the duration control sub-circuit includes: a first transistor to a seventh transistor and a first capacitor, the current control sub-circuit includes: an eighth transistor to a thirteenth transistor, a second capacitor and a third capacitor, and the reset sub-circuit includes: a fourteenth transistor;
In an exemplary implementation, the third transistor and the eighth transistor are of opposite transistor types, a transistor type of the fifth transistor and the sixth transistor is opposite to a transistor type of the twelfth transistor and the thirteenth transistor, and the eighth transistor and the ninth transistor are of opposite transistor types.
In an exemplary implementation, the first transistor to the seventh transistor, the ninth transistor, the eleventh transistor, and the fourteenth transistor are P-type transistors, and the eighth transistor, the tenth transistor, the twelfth transistor, and the thirteenth transistor are N-type transistors.
In an exemplary implementation, when a signal of the first reset signal line is an effective level signal, signals of the first scan signal line, the second scan signal line, the first light emitting signal line, the second light emitting signal line, the third scan signal line, and the second reset signal line are ineffective level signals;
In an exemplary implementation, when the signal of the first light emitting signal line is an effective level signal, a signal of the control signal line is a ramp signal and a voltage value of the signal of the control signal line is gradually decreased;
In a second aspect, the present disclosure further provides a display device, which includes multiple sub-modules, at least one of the sub-modules includes multiple rows of sub-pixels, and at least one of the sub-pixels includes the aforementioned pixel drive circuit and a light emitting device driven by the pixel drive circuit.
In an exemplary implementation, any one of the first reset signal line, the third scan signal line, the second reset signal line, the second scan signal line, the first light emitting signal line, and the second light emitting signal line connected to pixel drive circuits of all sub-pixels in a same sub-module has a same signal;
In a third aspect, the present disclosure further provides a method for driving a pixel drive circuit and the method is configured to drive the aforementioned pixel drive circuit;
Other aspects may be comprehended upon reading and understanding drawings and detailed description.
Accompanying drawings are used for providing further understanding of technical solutions of the present disclosure, constitute a part of the specification, and are used for explaining the technical solutions of the present disclosure together with embodiments of the present disclosure, but do not constitute limitations on the technical solutions of the present disclosure. Shapes and sizes of various components in the drawings do not reflect actual scales, but are only intended to schematically illustrate contents of the present disclosure.
To make the objectives, technical solutions, and advantages of the present disclosure clearer, the embodiments of the present disclosure will be described in detail below with reference to the accompany drawings. It is to be noted that implementations may be implemented in various forms. Those of ordinary skills in the art can easily understand such a fact that implementations and contents may be transformed into various forms without departing from the purpose and scope of the present disclosure. Therefore, the present disclosure should not be explained as being limited to the contents recorded in the following implementations only. The embodiments and features in the embodiments of the present disclosure may be randomly combined with each other if there is no conflict. In order to keep following description of the embodiments of the present disclosure clear and concise, detailed description of part of known functions and known components are omitted in the present disclosure. The drawings in the embodiments of the present disclosure relate only to the structures involved in the embodiments of the present disclosure, and other structures may be described with reference to conventional designs.
Scales of the drawings in the present disclosure may be used as a reference in actual processes, but are not limited thereto. For example, a width-length ratio of a channel, a thickness and spacing of each film layer, and a width and spacing of each signal line may be adjusted according to actual needs. A quantity of pixels in a display device and a quantity of sub-pixels in each pixel are not limited to the quantity shown in the drawings. The drawings described in the present disclosure are schematic structural diagrams only, and one implementation of the present disclosure is not limited to the shapes or numerical values, or the like shown in the drawings.
Ordinal numerals “first”, “second”, “third”, and the like in the specification are set not to form limits in numbers but only to avoid confusion between composition elements.
In the specification, for convenience, expressions “central”, “above”, “below”, “front”, “back”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside” and the like indicating directional or positional relationships are used to illustrate positional relationships between the composition elements, not to indicate or imply that involved devices or elements are required to have specific orientations and be structured and operated with the specific orientations but only to easily and simply describe the present specification, and thus should not be understood as limitations on the present disclosure. The positional relationships between the composition elements may be changed as appropriate according to a direction according to which each composition element is described. Therefore, appropriate replacements based on situations are allowed, which is not limited to the expressions in the specification.
In the specification, unless otherwise specified and defined, terms “mounting”, “mutual connection”, and “connection” should be understood in a broad sense. For example, a “connection” may be a fixed connection, or a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection, or an indirect connection through a middleware, or internal communication between two elements. Those of ordinary skills in the art can understand specific meanings of the above terms in the present disclosure according to specific situations.
In the specification, a transistor refers to an element that at least includes three terminals, i.e., a gate electrode, a drain electrode, and a source electrode. The transistor has a channel region between the drain electrode (drain electrode terminal, drain region, or drain) and the source electrode (source electrode terminal, source region, or source), and a current can flow through the drain electrode, the channel region, and the source electrode. It is to be noted that in the specification, the channel region refers to a region through which a current mainly flows.
In the specification, a first electrode may be a drain electrode, and a second electrode may be a source electrode. Or, the first electrode may be a source electrode, and the second electrode may be a drain electrode. In a case that transistors with opposite polarities are used, or in a case that a direction of a current changes during operation of a circuit, or the like, functions of the “source electrode” and the “drain electrode” are sometimes interchangeable. Therefore, the “source electrode” and the “drain electrode” are interchangeable in the specification.
In the specification, “electrical connection” includes a connection of composition elements through an element with a certain electrical action. An “element with a certain electrical action” is not particularly limited as long as electrical signals between the connected composition elements may be sent and received. Examples of the “element with the certain electrical action” not only include an electrode and a wire, but also include a switch element such as a transistor, a resistor, an inductor, a capacitor, another element with various functions, etc.
In the specification, “parallel” refers to a state in which an angle formed by two straight lines is −10° or more and 10° or less, and thus also includes a state in which the angle is −5° or more and 5° or less. In addition, “perpendicular” refers to a state in which an angle formed by two straight lines is 80° or more and 100° or less, and thus also includes a state in which the angle is 85° or more and 95° or less.
In the specification, a “film” and a “layer” are interchangeable. For example, a “conductive layer” may be replaced with a “conductive film” sometimes. Similarly, an “insulation film” may be replaced with an “insulation layer” sometimes.
In the specification, “disposed in a same layer” refers to a structure formed by patterning two (or more than two) structures through a same patterning process, and their materials may be the same or different. For example, materials of precursors for forming multiple structures disposed in a same layer are the same, and final materials may be the same or different.
Triangle, rectangle, trapezoid, pentagon, hexagon, etc. in this specification are not strictly defined, and they may be approximate triangle, rectangle, trapezoid, pentagon, hexagon, etc. There may be some small deformations caused by tolerance, and there may be chamfer, arc edge, deformation, etc.
In the present disclosure, “about” refers to that a boundary is not defined so strictly and numerical values within a range of process and measurement errors are allowed.
A display device includes multiple sub-modules, a sub-module includes multiple sub-pixels, and a sub-pixel includes multiple pixel drive circuits. A pixel drive circuit includes two parts, one of the two parts is a part for determining a light emitting duration, and the other of the two parts is a part for generating a constant current. Response time of the constant current generated by a pixel drive circuit is long, which makes the pixel drive circuit unable to control a gray scale performance accurately.
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In an exemplary implementation, as shown in
In an exemplary implementation, the first power supply line supply VDD1 may continuously provide a high voltage power supply signal and the second power supply line supply VDD2 may continuously provide a high voltage power supply signal. A voltage value of the signal of the first power supply line VDD1 and a voltage value of the signal of the second power supply line VDD2 may be the same or may be different.
In an exemplary implementation, the voltage value of the signal of the first power supply line VDD1 or the second power supply line VDD2 may be about 2.5 volts (V) to 3 volts (V), and for example, the voltage value of the signal of the first power supply line VDD1 or the second power supply line VDD2 may be about 2.8 volts (V).
In an exemplary implementation, the third power supply line VSS may continuously provide a low voltage power supply signal.
In an exemplary implementation, a voltage value of the signal of the third power supply line VSS may be about −3 volts (V) to −3.5 volts (V) and the voltage value of the signal of the third power supply line VSS may be about −3. 2 volts (V).
In an exemplary embodiment, the light emitting device which includes a current-driven device, may be a current-type light emitting diode, such as a micro light emitting diode (Micro LED for short), or a mini light emitting diode (Mini LED for short), or an organic light emitting diode (OLED for short), or a quantum light emitting diode (QLED for short). A typical size (e.g., a length) of a Micro-LED may be less than 100 μm, e.g., 10 μm to 50 μm. A typical size (e.g., a length) of a Mini-LED may be about 100 μm to 300 μm, e.g., 120 μm to 260 μm.
In an exemplary implementation, the light emitting device L may further include an organic emitting layer located between the first electrode and the second electrode.
In an exemplary implementation, the organic emitting layer may include a Hole Injection Layer (HIL), a Hole Transport Layer (HTL), an Electron Block Layer (EBL), an Emitting Layer (EML), a Hole Block Layer (HBL), an Electron Transport Layer (ETL), and an Electron Injection Layer (EIL) that are stacked. In an exemplary implementation, hole injection layers of all sub-pixels may be connected together to be a common layer, electron injection layers of all the sub-pixels may be connected together to be a common layer, hole transport layers of all the sub-pixels may be connected together to be a common layer, electron transport layers of all the sub-pixels may be connected together to be a common layer, hole block layers of all the sub-pixels may be connected together to be a common layer, emitting layers of adjacent sub-pixels may be overlapped slightly or may be isolated, and electron block layers of adjacent sub-pixels may be overlapped slightly or may be isolated.
The pixel drive circuit provided in the present disclosure is configured to drive a light emitting device to emit light. The light emitting device includes a first electrode and a second electrode. The pixel drive circuit includes a current control sub-circuit and a duration control sub-circuit. The duration control sub-circuit is electrically connected to a first scan signal line, a first reset signal line, a first light emitting signal line, a control signal line, a data signal line, an initial signal line, a first power supply line and a first node respectively, and is configured to provide a control signal to the first node under control of signals of the first scan signal line, the first reset signal line, the first light emitting signal line, the control signal line, the data signal line, the initial signal line and the first power supply line. The current control sub-circuit is electrically connected to a second scan signal line, a third scan signal line, a second light emitting signal line, a data signal line, a second power supply line, the first node and a first electrode of the light emitting device respectively, and is configured to provide a drive current to the first electrode of the light emitting device under control of signals of the first node, the second scan signal line, the third scan signal line, the second light emitting signal line, the data signal line and the second power supply line. A second electrode of the light emitting device is electrically connected to the third power supply line. The current control sub-circuit in the present disclosure can reduce response time of a drive current generated by the pixel drive circuit through control of multiple signal lines, and is suitable for a high resolution display product.
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An exemplary structure of the duration control sub-circuit is shown in
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An exemplary structure of a current control sub-circuit is shown in
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An exemplary structure of a reset sub-circuit is shown in
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In an exemplary implementation, the first transistor T1 may be referred to as a second node reset transistor. When a signal of the first reset signal line Reset1 is an effective level signal, a signal of the initial signal line INIT is written to the second node N2.
In an exemplary implementation, the second transistor T2 may be referred to as a first compensation transistor. When a signal of the first scan signal line Gate1 is an effective level signal, a signal of the fourth node N4 is written to the second node N2 to compensate the second node N2.
In an exemplary implementation, the third transistor T3 may be referred to as a first drive transistor. The third transistor T3 determines a control signal flowing between the first power supply line VDD1 and the first node N1 according to a potential difference between the gate electrode and the first electrode of the third transistor T3.
In an exemplary implementation, the fourth transistor T4 may be referred to as a first write transistor. When the signal of the first scan signal line Gate1 is an effective level signal, a signal of the data signal line Data is written to the third node N3.
In an exemplary implementation, the fifth transistor T5 and the sixth transistor T6 may be referred to as output transistors. When a signal of the first light emitting signal line EM1 is an effective level signal, the fifth transistor T5 and the sixth transistor T6 form a pathway between the first power supply line VDD1 and the first node N1.
In an exemplary implementation, the seventh transistor T7 may be referred to as a first node reset transistor. When the signal of the first reset signal line Reset1 is an effective level signal, a signal of the initial signal line INIT is written to the first node N1.
In an exemplary implementation, the eighth transistor T8 may be referred to as a second compensation transistor. When a signal of the third scan signal line Gate3 is an effective level signal, a signal of the fifth node N5 is written to the first node N1 to compensate the first node N1.
In an exemplary implementation, the ninth transistor T9 may be referred to as a third compensation transistor. When a signal of the second scan signal line Gate2 is an effective level signal, a signal of the sixth node N6 is written to the first node N1 to compensate the first node N1.
In an exemplary implementation, the tenth transistor T10 may be referred to as a second drive transistor. The tenth transistor T10 determines a drive current flowing between the second power supply line VDD2 and the third power supply line VSS according to a potential difference between the gate electrode and the first electrode of the tenth transistor T10.
In an exemplary implementation, the eleventh transistor T11 may be referred to as a second write transistor. When a signal of the second scan signal line Gate2 is an effective level signal, the signal of the data signal line Data is written to the fifth node N5.
In an exemplary implementation, the twelfth transistor T12 and the thirteenth transistor 13 may be referred to as light emitting transistors. When a signal of the second light emitting signal line EM2 is an effective level signal, the twelfth transistor T12 and the thirteenth transistor 13 drive the light emitting device L to emit light by forming the current path for a drive current between the second power supply line VDD2 and the third power supply line VDD.
In an exemplary implementation, the fourteenth transistor T14 may be referred to as an anode reset transistor. When a signal of the second reset signal line Reset2 is an effective level signal, a signal of the third power supply line VSS is written to the first electrode (anode) of the light emitting device L.
Transistors may be divided into N-type transistors and P-type transistors according to their characteristics. When a transistor is a P-type transistor, a turn-on voltage is a low level voltage (e.g., 0V, −5 V, −10 V, or another suitable voltage), and a turn-off voltage is a high level voltage (e.g., 5 V, 10 V, or another suitable voltage). When a transistor is an N-type transistor, the turn-on voltage is a high level voltage (e.g., 5 V, 10 V, or another suitable voltage), and the turn-off voltage is a low level voltage (e.g., 0 V, −5 V, −10 V, or another suitable voltage).
In an exemplary implementation, the first transistor T1 to the fourteenth transistor T14 may be P-type transistors, or may be N-type transistors. Use of a same type of transistors in a pixel drive circuit may simplify a process flow, reduce a process difficulty of a display panel, and improve a product yield. In some possible implementations, the first transistor T1 to the fourteenth transistor T14 may include a P-type transistor and an N-type transistor.
In an exemplary implementation, for the first transistor T1 to the fourteenth transistor T14, low temperature poly-crystalline silicon thin film transistors may be used, or oxide thin film transistors may be used, or both a low temperature poly-crystalline silicon thin film transistor and an oxide thin film transistor may be used. An active layer of a low temperature poly-crystalline silicon thin film transistor may be made of Low Temperature Poly-crystalline silicon (LTPS for short), and an active layer of an oxide thin film transistor may be made of an oxide semiconductor (Oxide). Low temperature poly-crystalline silicon thin film transistors have advantages such as high migration rate and fast charging, and oxide thin film transistors have advantages such as low leakage current. The low temperature poly-crystalline silicon thin film transistors and the oxide thin film transistors are integrated on one display device to form a low temperature poly-crystalline oxide (LTPO) display device, so that the advantages of both the low temperature poly-crystalline silicon thin film transistors and the oxide thin film transistors can be utilized, low frequency driving can be achieved, power consumption can be decreased, and display quality can be improved.
In an exemplary implementation, the third transistor T3 and the eighth transistor T8 are of opposite transistor types.
In an exemplary implementation, a transistor type of the fifth transistor T5 and the sixth transistor T6 is opposite to a transistor type of the twelfth transistor T12 and the thirteenth transistor T13.
In an exemplary implementation, the eighth transistor T8 and the ninth transistor T9 are of opposite transistor types.
In an exemplary implementation, the first transistor T1 to the seventh transistor T7, the ninth transistor T9, the eleventh transistor T11, and the fourteenth transistor T14 may be P-type transistors.
In an exemplary implementation, the eighth transistor T8, the tenth transistor T10, the twelfth transistor T12, and the thirteenth transistor T13 are N-type transistors. Among them, an N-type transistor may be an oxide thin film transistor or a low-temperature poly-crystalline silicon thin film transistor.
In an exemplary implementation, when a signal of the first reset signal line Reset1 is an effective level signal, signals of the first scan signal line Gate1, the second scan signal line Gate2, the first light emitting signal line EM1, the second light emitting signal line EM2, the third scan signal line Gate3, and the second reset signal line Reset2 are ineffective level signals.
In an exemplary implementation, when a signal of the first scan signal line Gate1 is an effective level signal, signals of the second scan signal line Gate2, the first reset signal line Reset1, the third scan signal line Gate3, the first light emitting signal line EM1, the second light emitting signal line EM2, and the second reset signal line Reset2 are ineffective level signals.
In an exemplary implementation, when a signal of the second scan signal line Gate2 is an effective level signal, a signal of the third scan signal line Gate3 is an effective level signal, and signals of the first scan signal line Gate1, the first reset signal line Reset1, the first light emitting signal line EM1, the second light emitting signal line EM2, and the second reset signal line Reset2 are ineffective level signals.
In an exemplary implementation, a signal of the first light emitting signal line EM1 and a signal of the second light emitting signal line EM2 are inverted signals for each other. When the signal of the first light emitting signal line EM1 is an effective level signal, the signal of the second light emitting signal line EM2 is an effective level signal and signals of the first scan signal line Gate1, the second scan signal line Gate2, the first reset signal line Reset1, the third scan signal line Gate3, and the second reset signal line Reset2 are ineffective level signals.
In an exemplary implementation, when the signal of the second reset signal line Reset2 is an effective level signal, the signal of the third scan signal line Gate3 is an effective level signal and signals of the first reset signal line Reset1, the first scan signal line Gate1, the second scan signal line Gate2, the first light emitting signal line EM1, and the second light emitting signal line EM2 are ineffective level signals.
In an exemplary implementation, occurrence time when the signal of the first scan signal line Gate1 is an effective level signal is earlier than occurrence time when the signal of the second scan signal line Gate2 is an effective level signal, and a duration for which the signal of the first scan signal line Gate1 is the effective level signal is less than a duration for which the signal of the second scan signal line Gate2 is the effective level signal.
In an exemplary implementation, when the signal of the first reset signal line Reset1 is an effective level signal, a signal of the initial signal line INIT is a first initial signal, and a voltage value of the first initial signal may be equal to a voltage value of a signal of the third power supply line. When the signal of the first reset signal line Reset1 is an ineffective level signal, the signal of the initial signal line INIT is a second initial signal, and a voltage value of the second initial signal may be equal to a voltage value of a signal of the first power supply line VDD1.
In an exemplary implementation, before the signal of the first light emitting signal line EM1 is the effective level signal, a signal of the control signal line SWP is a first control signal, and the first control signal is a constant voltage signal, a voltage value of the first control signal may be 5 volts to 7 volts, and for example the voltage value of the first control signal may be 6 volts. When the signal of the first light emitting signal line EM1 is the effective level signal, the signal of the control signal line SWP is a second control signal, and the second control signal is a ramp signal, and a voltage value of the second control signal is gradually decreased until it drops to 0 volt. After the signal of the first light emitting signal line EM1 is the effective level signal, the signal of the control signal line SWP is restored to the first control signal.
In an exemplary implementation, the working process of the pixel drive circuit may include following stages.
In a first stage P1, which is referred to as an initialization stage, signals of the first reset signal line Reset1, the third scan signal line Gate3, and the second light emitting signal line EM are low level signals, and signals of the first scan signal line Gate1, the second scan signal line Gate2, the first light emitting signal line EM1, and the second reset signal line Reset2 are high level signals. A signal of the first reset signal line Reset1 is a low level signal, so that the first transistor T1 and the seventh transistor T7 are turned on, an initial signal of the initial signal line INIT is written to a second node N2 through the turned-on first transistor T1 to initialize (reset) the second node N2 and clear the pre-stored voltage in the second node N2 to complete initialization, and the initial signal of the initial signal line INIT is written to a first node N1 through the turned on-seventh transistor T7 to initialize (reset) the first node N1 and clear the pre-stored voltage in the first node N1 to complete initialization. Signals of the first scan signal line Gate1 and the first light emitting signal line EM1 are high level signals, so that the second transistors T2, the fourth transistor T4, the fifth transistor T5, and the sixth transistor T6 are turned off, a signal of the second scan signal line Gate2 is a high level signal, so that the ninth transistors T9 and the eleventh transistors T11 are turned off, signals of the third scan signal line Gate3 and the second light emitting signal line EM are low level signals, and the eighth transistor T8, the twelfth transistor T12 and the thirteenth transistor T13 are turned off. At this time, a difference between voltage values of signals of the second node N2 and the third node N3 is less than a threshold voltage of the third transistor T3, and the third transistor T3 is turned on. Voltage value of a signal between the first node N1 and the fifth node N5 is greater than a threshold voltage of the tenth transistor T10, and the tenth transistor T10 is turned on. A signal of the second reset signal line Reset2 is a high level signal, so that the fourteenth transistor T14 is turned off. The light emitting device L does not emit light in this stage.
In a second stage P2, which is referred to as a first data write stage or a first threshold compensation stage, signals of the third scan signal line Gate3 and the second light emitting signal line EM are low level signals, and signals of the first reset signal line Reset1, the second scan signal line Gate2, the first light emitting signal line EM1 and the second reset signal line Reset2 are high level signals. The second stage P2 includes a first sub-stage P21 and a second sub-stage P22, occurrence time of the first sub-stage P21 may be before, within or after occurrence time of the second sub-stage P22, depending on a location of the pixel drive circuit. In
In the first sub-stage P21, a first data signal is written to the data signal line Data, a signal of the first scan signal line Gate1 is a low level signal, so that the second transistor T2 and the fourth transistor T4 are turned on, the first data signal is charged to the second node N2 through the turned-on fourth transistor T4, the third node N3, the turned on third transistor T3, the fourth node N4, and the turned-on second transistor T2 until a voltage value of a signal of the second node N2 satisfies V2=Vdata1−Vth3, where Vdata is a voltage value of the first data signal and Vth3 is a threshold voltage of the third transistor, signals of the first reset signal line Reset1 and the first light emitting signal line EM1 are high level signals, and the first transistor T1, the fifth transistor T5, the sixth transistor T6, and the seventh transistor T7 are turned off. The signal of the second scan signal line Gate2 is a high level signal, so that the ninth transistor T9 and the eleventh transistor T11 are turned off, signals of the third scan signal line Gate3 and the second light emitting signal line EM are low level signals, and the eighth transistor T8, the twelfth transistor T12, and the thirteenth transistor T13 are turned off. The signal of the second reset signal line Reset2 is a high level signal, so that the fourteenth transistor T14 is turned off. The light emitting device L does not emit light in this stage.
In the second sub-stage P22, the signal of the first scan signal line Gate1 is a low level signal, so that the second transistor T2 and the fourth transistor T4 are turned off, the signal of the second node N2 is kept to be the high level signal of the previous stage under an action of the first capacitor C1, the signals of the first reset signal line Reset1 and the first light emitting signal line EM1 are high level signals, so that the first transistor T1, the fifth transistor T5, the sixth transistor T6, and the seventh transistor T7 are turned off. The signal of the second scan signal line Gate2 is a high level signal, so that the ninth transistor T9 and the eleventh transistor T11 are turned off, the signals of the third scan signal line Gate3 and the second light emitting signal line EM are low level signals, so that the eighth transistor T8, the twelfth transistor T12, and the thirteenth transistor T13 are turned off. The signal of the second reset signal line Reset2 is a high level signal, so that the fourteenth transistor T14 is turned off. The light emitting device L does not emit light in this stage.
In a third stage P3, which is referred to as a second data write stage or a second threshold compensation stage, signals of the second scan signal line Gate2 and the second light emitting signal line EM2 are low level signals, signals of the first scan signal line Gate1, the first reset signal line Reset1, the third scan signal line Gate3, the first light emitting signal line EM1, and the second reset signal line Reset2 are high level signals, so that a second data signal is written to the data signal line Data. A signal of the third scan signal line Gate3 is a high level signal, so that the eighth transistor T8 is turned on, the signal of the second scan signal line Gate2 is a low level signal, so that the ninth transistor T9 and the eleventh transistor T11 are turned on, the second data signal is written to the fifth node N5 through the turned-on eleventh transistor T11, and a signal of the fifth node N5 is charged to the first node N1 through the turned-on eighth transistor T8, the turned-on tenth transistor T10, the sixth node N6, and the turned-on ninth transistor T9 respectively, until a voltage value of a signal of the first node N1 satisfies V1=Vdata2+Vth10, where Vdata2 is a voltage value of the second data signal and Vth10 is a threshold voltage of the tenth transistor. The signal of the first scan signal line Gate1 is a high level signal, so that the second transistor T2 and the fourth transistor T4 are turned off, the signals of the first reset signal line Reset1 and the first light emitting signal line EM1 are high level signals, so that the first transistor T1, the fifth transistor T5, the sixth transistor T6, and the seventh transistor T7 are turned off. A signal of the second light emitting signal line EM2 is a low level signal so that the twelfth transistor T12 and the thirteenth transistor T13 are turned off. The signal of the second reset signal line Reset2 is a high level signal, so that the fourteenth transistor T14 is turned off. The light emitting device L does not emit light in this stage.
In a fourth stage P4, which is referred to as a light emitting stage, signals of the first light emitting signal line EM1 and the third scan signal line Gate3 are low level signals, signals of the first scan signal line Gate1, the second scan signal line Gate2, the first reset signal line Reset1, the second light emitting signal line EM2, and the second reset signal line Reset2 are high level signals, and a signal of the control signal line SWP is a ramp signal, and a voltage value of the signal is gradually decreased. The signal of the first light emitting signal line EM1 is a low level signal, so that the fifth transistor T5 and the sixth transistor T6 are turned on, and a power supply signal output from a first high level power supply line VDD1 provides a drive signal to the first node N1 through the turned-on fifth transistor T5, the third node N3, the third transistor T3, the fourth node N4, and the sixth transistor T6. At this time, the signal of the first node N1 jumps under an action of the second capacitor C2 and the third capacitor C3, so that a voltage value of the signal of the first node N1 satisfies V1=Vdata2+Vth10+ΔV, where ΔV is a jump voltage value, the signal of the second light emitting signal line EM2 is a high level signal, so that the twelfth transistor T12 and the thirteenth transistor T13 are turned on, a power supply signal output from a second high level power supply line VDD2 provides a drive current to the seventh node N7 through the turned-on twelfth transistor T12, the fifth node N5, the tenth transistor T10, the sixth node N6, and the thirteenth transistor T13 to drive the light emitting device L to emit light, a signal of the second reset signal line Reset2 is a high level signal, and the fourteenth transistor T14 is turned off, which does not affect normal light emitting of the light emitting device. Since the voltage value of the signal of the control signal line SWP is gradually decreased, a voltage value of the signal of the second node N2 is also gradually decreased under an action of the first capacitor C1, and a conduction degree of the third transistor T3 is decreased until the third transistor T3 is completely turned off. After the third transistor T3 is completely turned off, the light emitting device L does not emit light.
In a fifth stage P5, which is referred to as a reset stage, signals of the second light emitting signal line EM2 and the second reset signal line Reset2 are low level signals, and signals of the first scan signal line Gate1, the second scan signal line Gate2, the first light emitting signal line EM1, the first reset signal line Reset1, and the third scan signal line Gate3 are high level signals. At this time, the first transistor T1 to the seventh transistor T7 and the ninth transistor T9 to the thirteenth transistor T13 are turned off. The signal of the third scan signal line Gate3 is a high level signal, so that the eighth transistor T8 is turned on, the signal of the second reset signal line Reset2 is a low level signal, so that the fourteenth transistor T14 is turned on, and a signal of the third power supply line VSS is written to the first electrode of the light emitting device L through the turned-on fourteenth transistor T14, so as to reset the first electrode of the light emitting device L and clear the pre-stored voltage in the first electrode of the light emitting device L.
In a drive process of the pixel drive circuit, a drive current flowing through the tenth transistor T10 (second drive transistor) is determined by a voltage difference between the gate electrode and the first electrode of the tenth transistor T10. Since a voltage of the first node N1 is Vdata2+Vth10+ΔV, a voltage value of the signal of the fifth node N5 is V5=Vdd2, where Vdd2 is a voltage value of a signal of the second high level power supply line, so the drive current of the tenth transistor T10 is:
Where I is the drive current flowing through the tenth transistor T10, that is, a drive current for driving the light emitting device L, K is a constant, and Vgs is the voltage difference between the gate electrode and the first electrode of the tenth transistor T10.
In an exemplary implementation, a picture displayed on the display substrate where the pixel drive circuit is located includes multiple display frames, and a duration of at least one display frame is from 8200 microseconds to 8400 microseconds, and for example may be 8300 microseconds.
In an exemplary implementation, a duration of the first stage in one display frame may be from 2450 microseconds to 2500 microseconds, and for example may be 2470 microseconds.
In an exemplary implementation, a duration of the second stage in one display frame may be from 15 microseconds to 25 microseconds, and for example may be 20 microseconds.
In an exemplary implementation, a duration of the third stage in one display frame may be from 15 microseconds to 25 microseconds, and for example may be 20 microseconds.
In an exemplary implementation, a duration of the fourth stage in one display frame may be from 5750 microseconds to 5800 microseconds, and for example may be 5770 microseconds.
In an exemplary implementation, a duration of the fifth stage in one display frame may be from 15 microseconds to 25 microseconds, and for example may be 20 microseconds.
It can be seen from a derivation result of the above current formula that in the light emitting stage, the drive current of the tenth transistor T10 is not affected by the threshold voltage of the tenth transistor T10. Therefore, influence of the threshold voltage of the tenth transistor T10 on the drive current is eliminated, which can ensure uniformity of the display brightness of the display product, and improve an overall display effect of the display product.
In the present disclosure, by providing the eighth transistor T8, the first node N1 can be quickly charged in the third stage, thus reducing response time of the pixel drive circuit to generate the drive current, and being applicable to high resolution display products. In the present disclosure, all transistors in the duration control sub-circuit are P-type transistors, while the tenth transistor (second drive transistor), the eighth transistor T8, the twelfth transistor T12, and the thirteenth transistor T13 in the current control sub-circuit are N-type transistors, so that a maximum drive current value of the pixel drive circuit can be kept stable regardless of a change of the first data signal, and a drive current maintenance rate is greater than 99.99%. A high drive current maintenance rate means that the pixel drive circuit can easily realize low frequency driving. Therefore, the pixel drive circuit provided by the present disclosure can not only realize high frequency driving, but also realize low frequency driving, which has a wide application range and can also realize accurate driving.
Table 1 shows data obtained by simulation test using the pixel drive circuit provided by the present disclosure. IMax is a maximum drive current value, CHR is a drive current maintenance rate, and Vdata1 is a voltage value of the first data signal. As shown in Table 1, voltage values of the first data signal are 5.6 V, 7.6 V, 9.6 V or after initialization, IMax deviation of the pixel drive circuit is not large, and IMax is basically stable at 249.99 uA, and CHR is all 100%.
In an exemplary implementation, response time of the generated drive current of the pixel drive circuit is from 220 microseconds to 270 microseconds and for example may be 250 microseconds.
An embodiment of the present disclosure further provides that a display device may include multiple sub-modules, at least one of the sub-modules includes multiple rows of sub-pixels, and at least one of the sub-pixels includes the aforementioned pixel drive circuit and a light emitting device driven by the pixel drive circuit.
The pixel drive circuit is the pixel drive circuit according to any one of the foregoing embodiments, and an implementation principle and implementation effects thereof are similar, which will not be repeated herein.
In an exemplary implementation, the display device may be any device that displays whether it is moving (for example, a video) or fixed (for example, a still image), and whether it is text or image. More specifically, the display device can be one of various electronic devices, can be implemented in or associated with various electronic devices. The various electronic devices include, for example, (but not limited to), a mobile phone, a VR apparatus, an AR apparatus, a wireless device, a Personal Data Assistant (PS1), a handheld or portable computer, a GPS receiver/navigator, a camera, an MP4 video player, a camcorder, a game console, a watch, a clock, a calculator, a TV monitor, a flat panel display, a computer monitor, a car monitor (e.g., an odometer display), a navigator, a cockpit controller and/or display, a camera view display (e.g., a display of a rear-view camera in a car), an electronic photo, an electronic billboards or sign, a projector, building structure, a package, and an aesthetic structure (e.g., an image display for a piece of jewelry). The form of the above-mentioned display device is not limited in the examples of the present disclosure.
In an exemplary implementation,
As shown in
As shown in
In an exemplary implementation, a sum of the first time corresponding to the pixel drive circuits of all row sub-pixels located in the same sub-module is a duration of the second stage of any one of the pixel drive circuits.
An embodiment of the present disclosure further provides a method for driving the pixel drive circuit, which is configured to drive the pixel drive circuit. The method for driving the pixel drive circuit may include:
The pixel drive circuit is the pixel drive circuit according to any one of the foregoing embodiments, and an implementation principle and implementation effects thereof are similar, which will not be repeated here.
The accompanying drawings of the present disclosure only involve the structures involved in the embodiments of the present disclosure, and other structures may refer to usual designs.
Although the implementations of the present disclosure are disclosed above, the contents are only implementations used for ease of understanding of the present disclosure, but not intended to limit the present disclosure. Any of those skilled in the art of the present disclosure can make any modifications and variations in the implementation mode and details without departing from the spirit and scope of the present disclosure. However, the protection scope of the present disclosure should be subject to the scope defined by the appended claims
From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the scope of the invention. Accordingly, the invention is not limited except as by the appended claims.
The present application is a continuation of International PCT Application No. PCT/CN2023/081830, filed on Mar. 16, 2023 and entitled “Pixel Drive Circuit and Driving Method Therefor, and Display Device”, which is hereby incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2023/081830 | Mar 2023 | WO |
| Child | 18665611 | US |
