Patent Grant
12057070
This application claims priority to Chinese Patent Application No. 202210753229.7, filed on Jun. 29, 2022, which is hereby incorporated by reference in its entirety.
The present application belongs to the field of display technology, and in particular, relates to a pixel circuit and a driving method thereof, and a display panel.
An organic light emitting diode (Organic Light Emitting Diode, OLED) display panel may include a plurality of sub-pixels arranged in an array, and each of the sub-pixels may include a pixel circuit and a light emitting element. A plurality of transistors are arranged in the pixel circuit. Based on mutual cooperation of the plurality of transistors, the pixel circuit transmits a driving current to the light emitting element to drive the light emitting element to emit light.
However, inventors of the present application found that some nodes in the pixel circuit have serious leakage, which caused the driving current transmitted by the pixel circuit to deviate from its standard value, thereby causing a deviation in a light emitting luminance of the light emitting element. In addition, when leakage time of the pixel circuits in different rows of the sub-pixels are different, the luminance of the light emitting elements in different rows of the sub-pixels are caused to be different, that is, a problem of uneven luminance is caused.
Embodiments of the present application provide a pixel circuit and a driving method thereof, and a display panel.
In a first aspect, embodiments of the present application provide a pixel circuit, including: a driving module, a control end of the driving module being electrically connected to a first node; a threshold compensation module, a control end of the threshold compensation module being electrically connected to a first scan signal line, a first end of the threshold compensation module being electrically connected to the first node, a second end of the threshold compensation module being electrically connected to a first end of the driving module; a first switch module, a control end of the first switch module being electrically connected to a first light emitting control signal line, a first end of the first switch module being electrically connected to the first end of the driving module; a second switch module, a control end of the second switch module being electrically connected to a second light emitting control signal line, a first end of the second switch module being electrically connected to a second end of the first switch module, a second end of the second switch module being electrically connected to a first electrode of the light emitting element; and a voltage regulator module, a first end of the voltage regulator module being electrically connected to a constant voltage signal line, a second end of the voltage regulator module being electrically connected to the target node. The target node is a connection node between the first end of the second switch module and the second end of the first switch module. The voltage regulator module is configured to maintain a potential of the target node. In a light emitting stage, the first switch module is turned on in response to a turn-on level of the first light emitting control signal line, the second switch module is turned on in response to a turn-on level of the second light emitting control signal line, and the light emitting element emits light.
In a second aspect, embodiments of the present application provide a driving method for a pixel circuit. The pixel circuit includes the pixel circuit according to the first aspect. The driving method includes: in a light emitting stage, providing a turn-on level to a first light emitting control signal line, providing a turn-on level to a second light emitting control signal line, such that a voltage signal of the first end of the driving module is transmitted to the target node through the turned-on first switch module.
In a third aspect, embodiments of the present application provides a display panel, including the pixel circuit according to the first aspect.
In order to more clearly illustrate technical solutions of embodiments of the present application, the drawings to be used in the embodiments of the present application will be briefly described. For those skilled in the art, other drawings can also be obtained from these drawings without any inventive effort.
Features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the objects, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the drawings and specific embodiments. It should be understood, that the specific embodiments described herein are only intended to explain the present application, but not to limit the present application. For those skilled in the art, the present application may be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present application by illustrating examples of the present application.
It should be noted that, relational terms herein such as first and second are used only for distinguishing one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms “comprising”, “including”, or any other variation thereof, are intended to encompass a non-exclusive inclusion, such that a process, a method, an article or a device including a series of elements includes not only those elements, but also includes other elements that are not explicitly listed or elements inherent to such a process, a method, an article or a device. Without further limitation, an element defined by “comprising . . . ” does not exclude presence of additional same elements in a process, a method, an article or a device that includes the element.
It should be understood that, the term “and/or” used herein is only a type of association relationship to describe associated objects, which indicates that there may be three types of relationships. For example, A and/or B may indicate the following three cases: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character “I” herein generally indicates that associated objects before and after the character have an “or” relationship.
It should be noted that transistors in the embodiments of the present application may be either N-type transistors or P-type transistors. For an N-type transistor, a turn-on level is a high level and a turn-off level is a low level. That is, when a gate of the N-type transistor is at a high level, a first electrode and a second electrode of the N-type transistor are turned on, and when the gate of the N-type transistor is at a low level, the first electrode and the second to electrode of the N-type transistor are turned off. For a P-type transistor, a turn-on level is a low level and a turn-off level is a high level. That is, when a control end of the P-type transistor is at a low level, a first electrode and a second electrode of the P-type transistor are turned on, and when the control end of the P-type transistor is at a high level, the first electrode and the second electrode of the P-type transistor are turned off. In specific implementations, the gates of the above transistors are used as control electrodes thereof. Moreover, according to signals and types of the gates of the transistors, the first electrode can be used as a source, and the second electrode can be used as a drain, or the first electrode can be used as a drain, and the second electrode can be used as a source, which will not be distinguished herein. In addition, the turn-on level and the turn-off level in the embodiments of the present application are generalized, the turn-on level refers to any level that can make a transistor turn on, and the turn-off level refers to any level that can make the transistor turn off.
In the embodiments of the present application, the term “electrically connected” may refer to a direct electrical connection between two components, or may refer to an electrical connection between two components via one or more other components.
In the embodiments of the present application, a first node, a second node and a third node are only defined to facilitate the description of a circuit structure, and the first node, the second node and the third node are not actual circuit units.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the present application. Accordingly, the present application is intended to cover the modifications and variations of the present application that fall within the scope of corresponding claims (claimed technical solutions) and their equivalents. It should be noted that, the implementations according to the embodiments of the present application may be combined with each other in the case of non-contradiction.
Before describing the technical solutions according to the embodiments of the present application, in order to facilitate understanding of the embodiments of the present application, the present application first specifically describes problems existing in the related art.
In addition, inventors of the present application further found that some types of current display apparatuses (such as hybrid TFT display apparatuses) usually use a one-drive-two design to narrow a border size, since a plurality set of scan drive signal lines are needed to drive sub-pixels to emit light. A hybrid TFT display apparatus (Hybrid TFT Display, HTD) is a display apparatus that has a thin film transistor (TFT) with indium gallium zinc oxide (IGZO) as an active layer and a TFT with polysilicon as the active layer in the pixel circuit. For the one-drive-two design, a scan drive circuit of the display apparatus includes a plurality of cascaded shift registers, each shift register may be electrically connected to two adjacent rows of scan signal lines, and each row of scan signal lines may be electrically connected to the pixel circuit in one row of sub-pixels. For example, as shown in
In this way, for the pixel circuit of the i-th row, during a period from when the pixel circuit of the i-th row writes a data signal to when the pixel circuit of the (i+1)-th row writes a data signal (that is, time of one row), the scan signal line S1 keeps outputting the turn-on level, the threshold compensation transistor M3′ in the pixel circuit of the i-th row is always in a turn-on state. For a period of time before the light emitting element D emits light, the light emitting control transistor M4′ is in a turn-on state, and the potential of the first electrode of the light emitting element D is lower than the potential of the first node N1. Therefore, a charge of the first node N1 is transmitted to the first electrode of the light emitting element D through the turned-on threshold compensation transistor M3′, the third node N3 and the turned-on light emitting control transistor M4′, that is, the first node N1 leaks a current to the first electrode of light emitting element D. For the pixel circuit of the (i+1)-th row, after the data signal is written into the pixel circuit of the i-th row, the scan signal line S1′ is switched to output the turn-off level in a short time, that is, the threshold compensation transistor M3′ in the pixel circuit of the (i+1)-th row is turned off very quickly. Therefore, a leakage amount of the first node N1 in the pixel circuit of the i-th row is greater than a leakage amount of the first node N1 in the pixel circuit of the (i+1)-th row, which causes that the light emitting element D connected to the pixel circuit of the i-th row is relatively bright, the light emitting element D connected to the pixel circuit of the (i+1)-th row is relatively dark, and therefore interlaced bright and dark lines appear. Especially for some wearable display apparatuses, the time for one row is 3 0˜50 us, and a difference in leakage amount of the first node N1 in the pixel circuit of the i-th row and the first node N1 in the pixel circuit of the (i+1)-th row is more obvious, which further causes that the luminance difference of the light emitting elements of adjacent rows is more obvious.
In view of the above research findings, the embodiments of the present application provide a pixel circuit and a driving method thereof, and a display panel, which can solve the technical problems in the related art that the light emitting luminance of the light emitting element deviates from a desired target luminance and that the luminance difference of the light emitting elements of adjacent rows is obvious.
The technical idea of the embodiments of the present application is as follows: a first switch module and a voltage regulator module are added in the pixel circuit, the first switch module is electrically connected to a first end (i.e., an output end) of a driving module, and the voltage regulator module is electrically connected to a target node between the first switch module and a second switch module. In a light emitting stage, the first switch module is turned on in response to a turn-on level of a first light emitting control signal line, and the second switch module is turned on in response to a turn-on level of a second light emitting control signal line, such that the potential of the target node is equal to the potential of the first end of the driving module, and the voltage regulator module maintains the potential of the target node. Since the voltage difference between the potential of the first end of the driving module and the potential of the first node (the node connected to a control end of the driving module) is small, the voltage difference between the potential of the target node and the potential of the first node is small. Therefore, a leakage current of the first node to the target node through the threshold compensation module can be effectively reduced, thereby effectively preventing a light emitting luminance of the light emitting element from deviating from a desired target luminance, and improving a luminance stability of the display panel; at the same time, improving or even eliminating a luminance difference of different rows of the light emitting elements, and improving a luminance uniformity of the display panel.
The pixel circuit according to the embodiments of the present application is first introduced below.
A control end of the first switch module 203 is electrically connected to a first light emitting control signal line EM1, and a first end of the first switch module 203 is electrically connected to the first end (i.e., the third node N3) of the driving module 201. A control end of the second switch module 204 is electrically connected to a second light emitting control signal line EM2, a first end of the second switch module 204 is electrically connected to a second end of the first switch module 203, and a second end of the second switch module 204 is electrically connected to the first electrode of the light emitting element D. The first electrode of the light emitting element D may be an anode of the light emitting element D. The anode of the light emitting element D may be formed of various electrically conductive materials. For example, the anode of the light emitting element D may be formed as a transparent electrode or a reflective electrode according to its use. When the anode is formed as a transparent electrode, it may be formed of, for example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), or indium oxide (In2O3). When the anode is formed as a reflective electrode, it may be formed of, for example, silver (Ag), magnesium (Mg), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr) or their mixtures.
A first end of the voltage regulator module 205 is electrically connected to a constant voltage signal line V1, and a second end of the voltage regulator module 205 is electrically connected to a target node Nm. The target node Nm is a connection node between the first end of the second switch module 204 and the second end of the first switch module 203, that is, the target node Nm is electrically connected to the first end of the second switch module 204 and the second end of the first switch module 203 at the same time. The constant voltage signal line V1 provides a constant voltage signal to the first end of the voltage regulator module 205, such that the voltage regulator module can maintain the potential of the target node Nm. In some examples, the constant voltage signal line V1 may be a positive voltage signal line that outputs a positive voltage signal, such as a positive voltage signal of +3V, +5V, or other positive voltage values. In other examples, the constant voltage signal line V1 may also be a negative voltage signal line that outputs a negative voltage signal, such as a negative voltage signal of −3V, −5V or other negative voltage values, which is not limited in the embodiments of the present application.
In a light emitting stage, the first switch module 203 is turned on in response to the turn-on level of the first light emitting control signal line EM1, the second switch module 204 is turned on in response to the turn-on level of the second light emitting control signal line EM2, and the light emitting element D emits light. The voltage signal (i.e., charge) of the third node N3 is transmitted to the target node Nm through the turned-on first switch module 203, such that the potential of the target node Nm is equal to the potential of the first end of the driving module 201 (i.e., the third node N3), and the voltage regulator module 205 maintains the potential of the target node Nm. For example, after measurement in some experiments, in the light emitting stage, the potential of the first node N1 is about 1˜2 volts, and the potential of the third node N3 is about 1.5 volts, that is, the voltage difference between the potential of the first node N1 and the potential of the third node N3 is only about −0.50.5 volts. However, in the related art, the voltage difference between the potential of the first node N1 and the potential of the first electrode of the light emitting element D is 4˜5 volts. Obviously, the voltage difference between the potential of the first node N1 and the potential of the third node N3 is significantly smaller than the voltage difference between the potential of the first node N1 and the potential of the first electrode of the light emitting element D.
Since the voltage difference between the potential of the first end of the driving module 201 (i.e., the third node N3) and the potential of the first node N1 is small, while the potential of the target node Nm is equal to the potential of the first end (i.e., the third node N1) of the driving module 201, the voltage difference between the potential of the target node Nm and the potential of the first node N1 is small. Therefore, the leakage current of the first node N1 to the target node Nm through the threshold compensation module can be effectively reduced, thereby effectively preventing the light emitting luminance of the light emitting element from deviating from the desired target luminance, and improving the luminance stability of the display panel; at the same time, improving or even eliminating the luminance difference of different rows of the light emitting elements, and improving the luminance uniformity of the display panel.
For example, during a period of time (referred to as a first time period) from when the first switch module 203 is turned on in a current frame to transmit the charge of the third node N3 to the target node Nm to when the first switch module 203 is turned on in a next frame to transmit the charge of the third node N3 to the target node Nm again, the potential of the target node Nm maintains a target potential, and the target potential is the potential of the third node N3 in the light emitting stage of the current frame. Then, in the first time period, since the voltage difference between the potential of the target node Nm and the potential of the first node N1 is small, the leakage current of the first node N1 to the target node Nm through the threshold compensation module can be effectively reduced.
A gate of the driving transistor MT is electrically connected to the first node N1, and a first electrode of the driving transistor MT is electrically connected to the third node N3.
A gate of the threshold compensation transistor M0 is electrically connected to the first scan signal line S1, a first electrode of the threshold compensation transistor M0 is electrically connected to the first node N1, and a second electrode of the threshold compensation transistor M0 is electrically connected to the third node N3.
A gate of the first transistor M1 is electrically connected to the first light emitting control signal line EM1, and a first electrode of the first transistor M1 is electrically connected to the third node N3. A gate of the second transistor M2 is electrically connected to the second light emitting control signal line EM2, a first electrode of the second transistor M2 is electrically connected to a second electrode of the first transistor M1, and a second electrode of the second transistor M2 is electrically connected to the first electrode of the light emitting element D.
A first electrode plate of the first storage capacitor C1 is electrically connected to the constant voltage signal line V1, and a second electrode plate of the first storage capacitor C1 is electrically connected to the target node Nm.
In the light emitting stage, the first transistor M1 is turned on in response to the turn-on level of the first light emitting control signal line EM1, and the second transistor M2 is turned on in response to the turn-on level of the second light emitting control signal line EM2. The voltage signal of the third node N3 is transmitted to the target node Nm through the turned-on first transistor M1, such that the potential of the target node Nm is equal to the potential of the third node N3, and the first storage capacitor C1 maintains the potential of the target node Nm. Since the voltage difference between the potential of the third node N3 and the potential of the first node N1 is small, while the potential of the target node Nm is equal to the potential of the third node N3, the voltage difference between the potential of the target node Nm and the potential of the first node N1 is small. Therefore, the leakage current of the first node N1 to the target node Nm through the threshold compensation transistor can be effectively reduced, thereby effectively preventing the light emitting luminance of the light emitting element from deviating from the desired target luminance, and improving the luminance stability of the display panel; at the same time, improving or even eliminating the luminance difference of different rows of the light emitting elements, and improving the luminance uniformity of the display panel.
The potential of the first node N1 is different in different stages among the initialization stage t1, the threshold compensation stage t2, and the light emitting stage t3. In the embodiment shown in
In the embodiments of the present application, the absolute value of the difference between the potential of the target node Nm and the potential of the first node N1 in the light emitting stage t3 may be less than 4 volts, that is, less than a voltage difference between the potential of the first node N1 and the potential of the first electrode of the light emitting element D in the related art. In this way, it can be ensured that the voltage difference between the potential of the target node Nm and the potential of the first node N1 is small, so the leakage current of the first node N1 to the target node Nm through the threshold compensation transistor can be effectively reduced, thereby effectively preventing the light emitting luminance of the light emitting element from deviating from the desired target luminance, and improving the luminance stability of the display panel; at the same time, improving or even eliminating the luminance difference of different rows of the light emitting elements, and improving the luminance uniformity of the display panel.
As shown in
In this way, a number of wirings in the display panel where the pixel circuit is located and a number of shift registers can be reduced, a wiring space can be saved, so as to facilitate realizing a narrow border.
With reference to
Since a potential change of the first node N1 in adjacent frames is small, the voltage difference between the potential of the first node N1 in the light emitting stage t3 of the i-th frame and the potential of the first node N1 in the light emitting stage t3 of the (i+1)-th frame is small. As analyzed above, in the light emitting stage, the voltage difference between the potential of the third node N3 and the potential of the first node N1 is small. Therefore, regardless of whether the potential of the target node Nm is the same as the potential of the third node N3 or the potential of the first node N1 in the light emitting stage t3 of a previous frame, at least in the light emitting stage of the current frame, the voltage difference between the potential of the target node Nm and the potential of the first node N1 is enabled to be small. Therefore, the leakage current of the first node N1 to the target node Nm through the threshold compensation module can be effectively reduced, thereby effectively preventing the light emitting luminance of the light emitting element from deviating from the desired target luminance, and improving the luminance stability of the display panel; at the same time, improving or even eliminating the luminance difference of different rows of the light emitting elements, and improving the luminance uniformity of the display panel.
As shown in
In this way, since the third switch module 601 is located between the threshold compensation module 202 and the third node N3, in the light emitting stage, the third switch module 601 is turned off, which can further reduce the leakage current of the first node N1 to the target node Nm through the threshold compensation module 202, thereby further effectively preventing the light emitting luminance of the light emitting element from deviating from the desired target luminance, and improving the luminance stability of the display panel; at the same time, improving or even eliminating the luminance difference of different rows of the light emitting elements, and further improving the luminance uniformity of the display panel.
In this way, before the light emitting stage t3, by resetting the second end of the voltage regulator module 205, it can be ensured that the potential of the third node N3 is successfully written to the target node Nm in the light emitting stage t3, or it can be ensured that the potential of the first node N1 is successfully written to the target node Nm in the reset stage t4.
A control end of the data writing module 801 is electrically connected to a fourth scan signal line S4, a first end of the data writing module 801 is electrically connected to the data voltage signal line data, a second end of the data writing module 801 is electrically connected to the second end of the driving module 201, and the data writing module 801 is configured to transmit a data voltage signal from the data voltage signal line data to the second end of the driving module 201, so as to write the data voltage signal into the pixel circuit. For convenience of description, a node to which the second end of the driving module 201 is connected is referred to as a second node N2.
A control end of the second reset module 802 is electrically connected to a fifth scan signal line S5, a first end of the second reset module 802 is electrically connected to the reference voltage signal line Vref, a second end of the second reset module 802 is electrically connected to the first node N1, and the second reset module 802 is configured to transmit the reference voltage signal from the reference voltage signal line Vref to the first node N1, so as to reset the first node N1.
A control end of the third reset module 803 is electrically connected to a sixth scan signal line S6, a first end of the third reset module 803 is electrically connected to the reference voltage signal line Vref, a second end of the third reset module 803 is electrically connected to the first electrode of the light emitting element D, and the third reset module 803 is configured to transmit the reference voltage signal from the reference voltage signal line Vref to the first electrode of the light emitting element D, so as to reset the first electrode of the light emitting element D.
A control end of the light emitting control module 804 is electrically connected to the second light emitting control signal line EM2, a first end of the light emitting control module 804 is electrically connected to a first power supply voltage signal line PVDD, and a second end of the light emitting control module 804 is electrically connected to the second end (i.e., the second node N2) of the driving module 201. The first power supply voltage signal line PVDD is configured to provide a positive voltage signal, such as a voltage signal of +3.3V or other positive voltage values.
A first electrode plate of the second storage capacitor C2 is electrically connected to the first power supply voltage signal line PVDD, a second electrode plate of the second storage capacitor C2 is electrically connected to the first node N1, and the second storage capacitor C2 is configured to maintain the potential of the first node N1.
Continuing to refer to
In this way, since a leakage current of an N-type transistor is smaller compared to that of a P-type transistor, if at least one of the threshold compensation module 202 and the second reset module 802 is an N-type transistor, the leakage current of the first node N1 can be further reduced, thereby further effectively preventing the light emitting luminance of the light emitting element from deviating from the desired target luminance, and improving the luminance stability of the display panel; at the same time, improving or even eliminating the luminance difference of different rows of the light emitting elements, and further improving the luminance uniformity of the display panel.
Continuing to refer to
In this way, since a leakage current of an oxide thin film transistor is small, if at least one of the threshold compensation module 202 and the second reset module 802 is an N-type transistor, the leakage current of the first node N1 can be further reduced, thereby further effectively preventing the light emitting luminance of the light emitting element from deviating from the desired target luminance, and improving the luminance stability of the display panel; at the same time, improving or even eliminating the luminance difference of different rows of the light emitting elements, and further improving the luminance uniformity of the display panel.
The second reset module 802 may include a fourth transistor M4, a gate of the fourth transistor M4 is electrically connected to the fifth scan signal line S5, a first electrode of the fourth transistor M4 is electrically connected to the reference voltage signal line Vref, a second electrode of the fourth transistor M4 is electrically connected to the first electrode of the light emitting element D, and the fourth transistor M4 is configured to transmit the reference voltage signal from the reference voltage signal line Vref to the first node N1, so as to reset the first node N1.
The third reset module 803 may include a fifth transistor M5, a gate of the fifth transistor M5 is electrically connected to the sixth scan signal line S6, a first electrode of the fifth transistor M5 is electrically connected to the reference voltage signal line Vref, a second electrode of the fifth transistor M5 is electrically connected to the first electrode of the light emitting element D, and the fifth transistor M5 is configured to transmit the reference voltage signal from the reference voltage signal line Vref to the first electrode of the light emitting element D, so as to reset the first electrode of the light emitting element D.
The light emitting control module 804 may include a sixth transistor M6, a gate of the sixth transistor M6 is electrically connected to the second light emitting control signal line EM2, a first electrode of the sixth transistor M6 is electrically connected to the first power supply voltage signal line PVDD, a second electrode of the sixth transistor M6 is electrically connected to the second end (i.e., the second node N2) of the driving module 201, and the sixth transistor M6 is configured to control the light emitting element D to emit light.
For convenience of understanding, a working process of the pixel circuit will be described below with reference to the pixel circuit shown in
In the initialization stage t1, the fifth scan signal line S5 outputs an electrically conductive level, the fourth scan signal line S4, the sixth scan signal line S6, the first light emitting control signal line EM1 and the second light emitting control signal line EM2 output a turn-off level, the fourth transistor M4 is turned on in response to the turn-on level transmitted by the fifth scan signal line S5, and the fourth transistor M4 is configured to transmit the reference voltage signal from the reference voltage signal line Vref to the first node N1, so as to reset the first node N1.
In the threshold compensation stage t2, the first scan signal line S1, the fourth scan signal line S4 and the sixth scan signal line S6 output a turn-on level, and the first light emitting control signal line EM1 and the second light emitting control signal line EM2 output a turn-off level. The threshold compensation transistor M0 is turned on in response to the turn-on level transmitted by the first scan signal line S1, and the third transistor M3 is turned on in response to the turn-on level transmitted by the fourth scan signal line S4, so as to realize writing of a data voltage signal and compensation for a threshold voltage. The fifth transistor M5 is turned on in response to the turn-on level transmitted by the sixth scan signal line S6, and is configured to transmit the reference voltage signal from the reference voltage signal line Vref to the first electrode of the light emitting element D, so as to reset the first electrode of the light emitting element D.
In the light emitting stage t3, the first light emitting control signal line EM1 and the second light emitting control signal line EM2 output a turn-on level, and the first scan signal line S1, the fourth scan signal line S4, the fifth scan signal line S5 and the sixth scan signal line S6 output a turn-off level. The first transistor M1 is turned on in response to the turn-on level transmitted by the first light emitting control signal line EM1, the second transistor M2 and the sixth transistor M6 are turned on in response to the turn-on level transmitted by the second light emitting control signal line EM2, and the voltage signal of the third node N3 is transmitted to the target node Nm through the turned-on first transistor M1, such that the potential of the target node Nm is equal to the potential of the third node N3, and the first storage capacitor C1 maintains the potential of the target node Nm. At the same time, a driving current of the driving transistor MT is transmitted to the first electrode of the light emitting element D through the first transistor M1 and the second transistor M2, and the light emitting element D emits light.
In some specific examples, optionally, the fourth scan signal line S4 and the sixth scan signal line S6 may be a same signal line, such that a number of wirings in the display panel where the pixel circuit is located and a number of shift registers can be reduced, a wiring space can be saved, so as to facilitate realizing a narrow border.
In some specific examples, optionally, the sixth scan signal line S6 and the fourth scan signal line S4 may not be a same signal line, and in the initialization stage t1, the sixth scan signal line S6 outputs a turn-on level; in the threshold compensation stage t2, the sixth scan signal line S6 outputs a turn-off level, thereby resetting the first electrode of the light emitting element D in the initialization stage t1.
In the reset stage t4, the first scan signal line S1 and the first light emitting control signal line EM1 output a turn-on level, and the fourth scan signal line S4, the fifth scan signal line S5, the sixth scan signal line S6 and the second light emitting control signal line EM2 output a turn-off level. The threshold compensation transistor M0 is turned on in response to the turn-on level of the first scan signal line S1, the first transistor M1 is turned on in response to the turn-on level of the first light emitting control signal line EM1, and the voltage signal (i.e., charge) of the first node N1 is sequentially transmitted to the target node Nm through the threshold compensation transistor M0 and the first transistor M1. The second transistor M2 is turned off in response to the turn-off level of the second light emitting control signal line EM2, preventing the light emitting element D from being lit.
The initialization stage t1, the threshold compensation stage t2 and the light emitting stage t3 in the embodiment shown in
In this way, since the seventh transistor M7 is located between the threshold compensation transistor M0 and the third node N3, in the light emitting stage, the seventh transistor M7 is turned off, which can further reduce the leakage current of the first node N1 to the target node Nm through the threshold compensation transistor M0, thereby further effectively preventing the light emitting luminance of the light emitting element from deviating from the desired target luminance, and improving the luminance stability of the display panel; at the same time, improving or even eliminating the luminance difference of different rows of the light emitting elements, and further improving the luminance uniformity of the display panel.
Continuing to refer to
In this way, before the light emitting stage t3, by resetting the second electrode plate of the first storage capacitor C1, it can be ensured that the potential of the third node N3 is successfully written to the target node Nm in the light emitting stage t3, or it can be ensured that the potential of the first node N1 is successfully written to the target node Nm in the reset stage t4.
In this way, the first sub-transistor M61 and the second sub-transistor M62 constitute a dual-gate transistor, which can reduce a current of the first power supply voltage signal line PVDD, thereby reducing the luminance of the light emitting element D to compensate for an influence on the luminance of the light emitting element D due to the leakage current of the first node N1, such that the luminance of the light emitting element D is close to the desired target luminance.
Inventors of the present application further found that when the display panel switches images (for example, switches from a black state to a white image), due to a hysteresis effect, there is a problem of deviation between an actual offset amount and a desired target offset amount of a threshold voltage Vth of the driving transistor. For example, the offset amount of the threshold voltage Vth is too large, such that the luminance of the light emitting element cannot reach a preset luminance, and a display effect of the display panel is affected.
In view of the above findings, the present application considers adjusting the threshold voltage Vth of the driving transistor to reduce the deviation between the actual offset amount and the desired target offset amount of the threshold voltage Vth and to improve the display effect of the display panel.
In this way, the threshold voltage Vth of the driving module 201 is adjusted by the offset compensation voltage, such that the threshold voltage Vth of the driving module 201 is adjusted in advance before the light emitting element D is driven to emit light, so as to reduce the deviation between the actual offset amount and the desired target offset amount of the threshold voltage Vth and improve the display effect of the display panel.
Continuing to refer to
According to some embodiments of the present application, optionally, the display panel where the pixel circuit 20 is located may adopt a one-drive-two design.
In this way, the first scan drive signal is provided to two adjacent rows of the pixel circuits through one first shift register 1601a, which can reduce the number of the first shift registers 1601a, and is beneficial to realize a narrow border while reducing a production cost.
In this way, the second scan drive signal is provided to two adjacent rows of the pixel circuits through one second shift register 1602a, which can reduce the number of the second shift registers 1602a, and is beneficial to realize a narrow border while reducing a production cost.
It should be noted that, for convenience of illustration, the first scan drive circuit 1601 and the second scan drive circuit 1602 are respectively shown in two drawings. However, in practice, the display panel 160 may include both the first scan drive circuit 1601 and the second scan drive circuit 1602.
In this way, scan drive signals can be provided to two adjacent rows of the pixel circuits through one shift register 1801a, which can reduce the number of shift registers 1801a, and is beneficial to realize a narrow border while reducing a production cost.
An arrangement of a film layer of the pixel circuit 20 will be described in detail below with reference to some specific embodiments.
Based on the pixel circuit 20 according to the above-mentioned embodiments, correspondingly, the embodiments of the present application further provide a specific implementation of a driving method for a pixel circuit. The driving method for the pixel circuit can be applied to the pixel circuit 20 according to the above-mentioned embodiments.
S101. In the light emitting stage, providing a turn-on level to the first light emitting control signal line and providing a turn-on level to the second light emitting control signal line, such that a voltage signal of the first end of the driving module is transmitted to the target node through the turned-on first switch module.
It should be noted that, a specific implementation process of step S101 has been described in detail above, and for brevity of description, will not be repeated herein.
In the driving method for the pixel circuit according to the embodiment of the present application, in the light emitting stage, the first switch module is turned on in response to the turn-on level of the first light emitting control signal line, the second switch module is turned on in response to the turn-on level of the second light emitting control signal line, and the voltage signal (i.e., charge) of the third node is transmitted to the target node through the turned-on first switch module, such that the potential of the target node is the same as the potential of the first end (i.e., the third node) of the driving module. Since the voltage difference between the potential of the first end (i.e., the third node) of the driving module and the potential of the first node is small, while the potential of the target node is the same as the potential of the first end (i.e., the third node) of the driving module, the voltage difference between the potential of the target node and the potential of the first node is small. Therefore, the leakage current of the first node to the target node through the threshold compensation module can be effectively reduced, thereby effectively preventing the light emitting luminance of the light emitting element from deviating from the desired target luminance, and improving the luminance stability of the display panel; at the same time, improving or even eliminating the luminance difference of different rows of the light emitting elements, and improving the luminance uniformity of the display panel.
According to some embodiments of the present application, optionally, time of a frame includes the initialization stage, the data writing stage, the light emitting stage, and the reset stage, the reset stage of an i-th frame is located after the light emitting stage of the i-th frame and before the initialization stage of a (i+1)-th frame, wherein i is a positive integer.
S102. In the reset stage, providing a turn-on level to the first scan signal line, and providing a turn-on level to the first light emitting control signal line, such that the voltage signal of the first node is transmitted to the target node sequentially through the threshold compensation module and the first switch module.
It should be noted that, a specific implementation process of step S102 has been described in detail above, and for brevity of description, will not be repeated herein.
In the reset stage, the threshold compensation module is turned on in response to the turn-on level of the first scan signal line, the first switch module is turned on in response to the turn-on level of the first light emitting control signal line, and the voltage signal (i.e., charge) of the first node is transmitted to the target node sequentially through the threshold compensation module and the first switch module. Since a potential change of the first node N1 in adjacent frames is small, the voltage difference between the potential of the first node N1 in the light emitting stage of the i-th frame and the potential of the first node N1 in the light emitting stage of the (i+1)-th frame is small. As analyzed above, in the light emitting stage, the voltage difference between the potential of the third node N3 and the potential of the first node N1 is small. Therefore, regardless of whether the potential of the target node Nm is the same as the potential of the third node N3 or the potential of the first node N1 in the light emitting stage of a previous frame, at least in the light emitting stage of the current frame, the voltage difference between the potential of the target node Nm and the potential of the first node N1 is enabled to be small. Therefore, the leakage current of the first node N1 to the target node Nm through the threshold compensation module can be effectively reduced, thereby effectively preventing the light emitting luminance of the light emitting element from deviating from the desired target luminance, and improving the luminance stability of the display panel; at the same time, improving or even eliminating the luminance difference of different rows of the light emitting elements, and improving the luminance uniformity of the display panel.
As shown in
Accordingly, the light emitting stage may include a first stage and a second stage. S101. In the light emitting stage, providing a turn-on level to the first light emitting control signal line and providing a turn-on level to the second light emitting control signal line, specifically includes the following steps:
In the first stage, providing a turn-on level to the seventh scan signal line, such that the offset compensation voltage signal from the offset compensation voltage signal line is transmitted to the second end of the driving module through the turned-on offset compensation module, so as to compensate for the threshold voltage of the driving module.
In the second stage, providing a turn-on level to the first light emitting control signal line, and providing a turn-on level to the second light emitting control signal line, such that the voltage signal of the first end of the driving module is transmitted to the target node through the turned-on first switch module and second switch module.
In this way, the threshold voltage Vth of the driving module 201 is adjusted by the offset compensation voltage, such that the threshold voltage Vth of the driving module 201 is adjusted in advance before the light emitting element D is driven to emit light, so as to reduce the deviation between the actual offset amount and the desired target offset amount of the threshold voltage Vth and improve the display effect of the display panel.
Based on the pixel circuit 20 according to the above-mentioned embodiments, correspondingly, the embodiments of the present application further provide a display panel.
As shown in
With reference to
In this way, the first scan drive signal is provided to two adjacent rows of the pixel circuits through one first shift register 1601a, which can reduce the number of the first shift registers 1601a, and is beneficial to realize a narrow border while reducing the production cost.
As shown in
With reference to
In this way, the second scan drive signal is provided to two adjacent rows of the pixel circuits through one second shift register 1602a, which can reduce the number of the second shift registers 1602a, and is beneficial to realize a narrow border while reducing the production cost.
With reference to
In this way, scan drive signals can be provided to two adjacent rows of the pixel circuits through one shift register 1801a, which can reduce the number of shift registers 1801a, and is beneficial to realize a narrow border while reducing the production cost.
It should be understood that, the specific structures of the pixel circuit and the display panel provided in the drawings of the embodiments of the present application are only some examples, and are not intended to limit the present application. In addition, in the case of non-contradiction, the above-mentioned embodiments provided in the present application may combine with each other.
In accordance with the embodiments of the present application as described above, these embodiments do not exhaustively describe all the details, nor do they limit the application to only the specific embodiments described. Obviously, many modifications and variations are possible in light of the above description. The detailed description of these embodiments are for a better explanation of principles and practical applications of the present application, to thereby enable those skilled in the art to best utilize the present application and various embodiments with various modifications. This application is limited only by the claims, along with their full scope and equivalents.
It should be clear that, various embodiments in the specification are described in a progressive way, and the same or similar parts of various embodiments may be referred to each other, and each embodiment focuses on the differences from other embodiments. For the embodiments of the display panel and the embodiments of the display apparatus, related parts may refer to the description parts of the embodiments of the pixel driving circuit and the embodiments of the array substrate. The present application is not limited to the specific structures described above and shown in the drawings. Various changes, modifications and additions can be made by those skilled in the art after they comprehend the spirit of the present application. And, for sake of brevity, a detailed description of the known technology is omitted herein.
Those skilled in the art should understand that the above-mentioned embodiments are all illustrative and non-restrictive. Different technical features appearing in different embodiments can be combined to achieve beneficial effects. Those skilled in the art should be able to understand and implement other modified embodiments of the disclosed embodiments on the basis of studying the drawings, the description, and the claims. In the claims, the term “comprising” does not exclude other structures, the number relates to “one” but does not exclude a plurality, the terms “first” and “second” are configured to indicate names and not to indicate any particular order. Any reference signs in the claims should not be construed as limiting the protection scope. The presence of certain technical features in different dependent claims does not mean that these technical features cannot be combined to obtain beneficial effects.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202210753229.7 | Jun 2022 | CN | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20230343294 | Guo | Oct 2023 | A1 |
| Number | Date | Country |
|---|---|---|
| 106886111 | Jun 2017 | CN |
| 112634832 | Apr 2021 | CN |
| 113707077 | Nov 2021 | CN |
| Number | Date | Country | |
|---|---|---|---|
| 20240005858 A1 | Jan 2024 | US |
