This application relates to the field of display technology, in particular a light-emitting driving circuit, a backlight module, and a display panel.
Mini light-emitting diodes (Mini LEDs) and micro light-emitting diodes (Micro LEDs) are collectively referred to as MLEDs, which, as a next generation of display technology, show better display characteristics, such as high contrast, high color gamut, high response speed, viewing angle, etc. Therefore, MLEDs are widely used in the field of high-performance displays.
The driving scheme of the MLED belongs to a current driving. On the one hand, different input data signals lead to different gate-source voltages (Vgs) of the drive transistor, so that the source-drain current (Ids) and the brightness of the MLED are different, which can realize gray-scale segmentation. On the other hand, since the drive transistor is operated in on-state during the entire display time, the driving current needs to be accurately controlled to achieve the purpose of gray-scale segmentation. Therefore, threshold voltage and mobility drift of the drive transistor have direct impacts on the driving current, resulting in an abnormal display. However, in the MLED, the current direction of the drive transistor is always the same, and under the combined effects of the long turn-on time and the fixed current direction, the effect of current bias (stress) is very obvious, which likely leads to a performance drift of the drive transistor, thereby reducing the stability of the drive transistor.
The present disclosure provides a light-emitting driving circuit, a backlight module, and a display panel to solve the technical problem in the prior arts that the drive transistor in the light-emitting driving circuit has an obvious current bias effect and hence the stability of the drive transistor is vulnerable.
The disclosure provides a light-emitting driving circuit. The light-emitting driving circuit includes a drive transistor, a data writing module, and a light-emitting module. A first electrode of the drive transistor is electrically connected to a first node, and a second electrode of the drive transistor is electrically connected to a first power signal. The data writing module is fed to a scan signal and a data signal, and is electrically connected to a gate of the drive transistor. The data writing module is configured to write the data signal to the gate of the drive transistor under a control of the scan signal. The light-emitting module includes at least one of the first light-emitting devices and at least one of the second light-emitting devices. A first terminal of the first light-emitting device and a second terminal of the second light-emitting device are both electrically connected to the first node. The second terminal of the first light-emitting device and the first terminal of the second light-emitting device are fed with a second power signal. The first power signal and the second power signal are configured to perform level conversion according to a preset period, so that a direction of a current flowing through the drive transistor is changed according to the preset period.
Optionally, in some embodiments of the present disclosure, the length of the preset period is at least one frame.
Optionally, in some embodiments of the present disclosure, the first power signal and the second power signal are configured to perform level conversion in a vertical blanking time between adjacent frames.
Optionally, in some embodiments of the present disclosure, the first power signal has a first high voltage level and a first low voltage level, and the first power signal is switched between the first high voltage level and the first low voltage level according to the preset period. The second power signal has a second high voltage level and a second low voltage level, and the second power signal is switched between the second high voltage level and the second low voltage level according to the preset period.
Optionally, in some embodiments of the present disclosure, the first high voltage level and the second high voltage level are the same, the first low voltage level and the second low voltage level are the same, and the first power signal and the second power signal are kept in antiphase.
Optionally, in some embodiments of the present disclosure, the data writing module includes a switch transistor and a storage capacitor.
The gate of the switch transistor is connected to the scan signal. A first electrode of the switch transistor is connected to the data signal. A second electrode of the switch transistor, one end of the storage capacitor, and the gate of the drive transistor are electrically connected. The other end of the storage capacitor is electrically connected to first electrode of the drive transistor.
Optionally, in some embodiments of the present disclosure, the light-emitting driving circuit further comprises a sensing module, the sensing module is connected to a sensing signal and a reset signal, and the sensing module is electrically connected to first electrode of the drive transistor. The sensing module is used to detect a threshold voltage of the drive transistor under the control of the sensing signal and the reset signal.
Optionally, in some embodiments of the present disclosure, the sensing module comprises a sensing transistor and a first switch unit. The gate of the sensing transistor is connected to the sensing signal. First electrode of the sensing transistor is electrically connected to one end of the first switch unit. A second electrode of the sensing transistor is electrically connected to first electrode of the drive transistor. The other end of the first switch unit is connected to the reset signal.
The present disclosure also provides a backlight module. The backlight module includes a data line configured to provide a data signal, a scan lines configured to provide a scan signal, a first power line configured to provide a first power signal, a second power line configured to provide a second power signal, and a light-emitting driving circuit.
The light-emitting driving circuit includes a drive transistor, a data writing module, and a light-emitting module. A first electrode of the drive transistor is electrically connected to a first node, and a second electrode of the drive transistor is electrically connected to a first power signal. The data writing module is fed to a scan signal and a data signal, and is electrically connected to a gate of the drive transistor. The data writing module is configured to write the data signal to the gate of the drive transistor under a control of the scan signal. The light-emitting module includes at least one of the first light-emitting devices and at least one of the second light-emitting devices. A first terminal of the first light-emitting device and a second terminal of the second light-emitting device are both electrically connected to the first node. The second terminal of the first light-emitting device and the first terminal of the second light-emitting device are fed with a second power signal. The first power signal and the second power signal are configured to perform level conversion according to a preset period, so that a direction of a current flowing through the drive transistor is changed according to the preset period.
Optionally, in some embodiments of the present disclosure, the length of the preset period is at least one frame.
Optionally, in some embodiments of the present disclosure, the first power signal and the second power signal are configured to perform level conversion in a vertical blanking time between adjacent frames.
Optionally, in some embodiments of the present disclosure, the first power signal has a first high voltage level and a first low voltage level, and the first power signal is switched between the first high voltage level and the first low voltage level according to the preset period.
The second power signal has a second high voltage level and a second low voltage level, and the second power signal is switched between the second high voltage level and the second low voltage level according to the preset period.
Optionally, in some embodiments of the present disclosure, the first high voltage level and the second high voltage level are the same, the first low voltage level and the second low voltage level are the same, and the first power signal and the second power signal are kept in antiphase.
Optionally, in some embodiments of the present disclosure, the data writing module comprises a switch transistor and a storage capacitor.
The gate of the switch transistor is connected to the scan signal. A first electrode of the switch transistor is connected to the data signal. A second electrode of the switch transistor, one end of the storage capacitor, and the gate of the drive transistor are electrically connected. The other end of the storage capacitor is electrically connected to first electrode of the drive transistor.
The present disclosure also provides a display panel. The display panel comprises a plurality of pixel units arranged in an array, each of which comprises a light-emitting driving circuit.
The light-emitting driving circuit includes a drive transistor, a data writing module, and a light-emitting module. A first electrode of the drive transistor is electrically connected to a first node, and a second electrode of the drive transistor is electrically connected to a first power signal. The data writing module is fed to a scan signal and a data signal, and is electrically connected to a gate of the drive transistor. The data writing module is configured to write the data signal to the gate of the drive transistor under a control of the scan signal. The light-emitting module includes at least one of the first light-emitting devices and at least one of the second light-emitting devices. A first terminal of the first light-emitting device and a second terminal of the second light-emitting device are both electrically connected to the first node. The second terminal of the first light-emitting device and the first terminal of the second light-emitting device are fed with a second power signal. The first power signal and the second power signal are configured to perform level conversion according to a preset period, so that a direction of a current flowing through the drive transistor is changed according to the preset period.
Optionally, in some embodiments of the present disclosure, the length of the preset period is at least one frame.
Optionally, in some embodiments of the present disclosure, the first power signal and the second power signal are configured to perform level conversion in a vertical blanking time between adjacent frames.
Optionally, in some embodiments of the present disclosure, the first power signal has a first high voltage level and a first low voltage level, and the first power signal is switched between the first high voltage level and the first low voltage level according to the preset period.
The second power signal has a second high voltage level and a second low voltage level, and the second power signal is switched between the second high voltage level and the second low voltage level according to the preset period.
Optionally, in some embodiments of the present disclosure, the first high voltage level and the second high voltage level are the same, the first low voltage level and the second low voltage level are the same, and the first power signal and the second power signal are kept in antiphase.
Optionally, in some embodiments of the present disclosure, the data writing module includes a switch transistor and a storage capacitor.
The gate of the switch transistor is connected to the scan signal. A first electrode of the switch transistor is connected to the data signal. A second electrode of the switch transistor, one end of the storage capacitor, and the gate of the drive transistor are electrically connected. The other end of the storage capacitor is electrically connected to first electrode of the drive transistor.
The present disclosure provides a light-emitting driving circuit, a backlight module, and a display panel. The light-emitting driving circuit includes a drive transistor, a data writing module, and a light-emitting module. The source and drain of the drive transistor are electrically connected to a first power signal and a first node, respectively. The light-emitting module includes at least one of the first light-emitting devices and at least one of the second light-emitting devices. Both the first terminal of the first light-emitting device and the second terminal of the second light-emitting device are electrically connected to the first node. Bothe the second terminal of the first light-emitting device and the first terminal of the second light-emitting device are electrically connected to a second power signal. The present disclosure configures the first power signal and the second power signal are configured to perform level conversion according to a preset period, so that the direction of the current flowing through the drive transistor is changed according to the preset period, thereby effectively improving the current bias of the drive transistor, avoiding the threshold voltage and mobility drift of the drive transistor, improving the stability of the drive transistor. In addition, since the first light-emitting device and the second light-emitting device are arranged in reverse directions, which can alternately emit light under the operation of the driving current, thereby achieving the purpose of reducing light efficiency and reducing dead pixels.
The technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments of this application, other embodiments derived by those skilled in the art without creative work shall fall within the protection scope of this application.
In addition, the terms “first”, “second”, etc. in the specification and claims of the present disclosure are used to distinguish different objects, rather than to describe a specific order. The terms “including” and “comprising” and any variations of them are intended to cover non-exclusive inclusion.
The present disclosure provides a light-emitting driving circuit, a backlight module, and a display panel, which will be described in detail below. It should be noted that the description order of the following embodiments is not intended to limit the preferred order of the embodiments of the present disclosure.
Please refer to
The first electrode of the drive transistor DT is electrically connected to the first node A. The second electrode of the drive transistor DT is electrically connected to the first power signal VDD. The data writing module 101 is connected to the scan signal Vsc and the data signal Vda, and is electrically connected to the gate of the drive transistor DT. The data writing module 101 is used to write the data signal Vda to the gate of the drive transistor DT under the control of the scan signal Vsc. The light-emitting module 102 includes at least one of the first light-emitting devices D1 and at least one of the second light-emitting devices D2. The first terminal of the first light-emitting device D1 and the second terminal of the second light-emitting device D2 are both electrically connected to the first node A. The second terminal of the first light-emitting device D1 and the first terminal of the second light-emitting device D2 are both electrically connected to the second power signal VSS. The first power signal VDD and the second power signal VSS are configured to perform level conversion according to a preset period, so that the direction of current flowing through the drive transistor DT is changed according to the preset period.
In the light-emitting driving circuit 100 of the present disclosure, since the first terminal of the first light-emitting device D1 and the second terminal of the second light-emitting device D2 are both electrically connected to the first node A, the second terminal of the first light-emitting device D1 and the first terminals of the second light-emitting device D2 are all electrically connected to the second power signal VSS. That is, the first light-emitting device D1 and the second light-emitting device D2 are arranged in reverse directions. Therefore, the first light-emitting device D1 and the second light-emitting device D2 do not emit light at the same time. Then, by converting the first power signal VDD and the second power signal VSS according to the preset period, the direction of the current flowing through the drive transistor DT can be changed according to the preset period, thereby effectively improving the current bias of the drive transistor DT, avoiding the threshold voltage and mobility drift of the drive transistor DT, improving the stability of the drive transistor DT. At the same time, when the direction of the driving current changes, the first light-emitting device D1 and the second light-emitting device D2 can alternately emit light to avoid abnormal light emission caused by the change of the direction of the driving current.
In addition, since the first light-emitting device D1 and the second light-emitting device D2 emit light alternately, the temperature of the first light-emitting device D1 and the second light-emitting device D2 will not be too high, thereby reducing the light efficiency. The current bias effect of the first light-emitting device D1 and the second light-emitting device D2 can also be suppressed. Furthermore, since each light-emitting module 102 has a first light-emitting device D1 and a second light-emitting device D2, when any one of them is damaged, the other one can continue to provide brightness, thereby reducing the impact of dead pixels.
The first light-emitting device D1 and the second light-emitting device D2 can be mini light-emitting diodes, micro light-emitting diodes or organic light-emitting diodes. When the first light-emitting device D1 and the second light-emitting device D2 are the above-mentioned light-emitting diodes. The first terminal of the first light-emitting device D1 may be one of the positive terminal or the negative terminal of the light-emitting diode. The second terminal of the first light-emitting device D1 may be the other one of the positive terminal or the negative terminal of the light-emitting diode. The same is true for the second light-emitting device D2, which will not be repeated here.
In this application, the length of the preset period is at least one frame. One frame represents the time for the display panel to display one frame. For example, the preset period can be 1 frame, 2 frames, 5 frames, 10 frames, etc., which can be specifically set according to specific parameters of the light-emitting driving circuit 100, hence is not limited in this application. Wherein, the first power signal VDD and the second power signal VSS can be provided by an external power chip (not shown in the figure), which is not addressed here. Further, the first power signal VDD and the second power signal VSS can be converted in level during the vertical blanking time between the current frame and the next adjacent frame, so as to avoid affecting the display screen of the display panel.
In this application, the voltage value of the first power signal VDD and the voltage value of the second power signal VSS can be set according to actual applications. It only needs to satisfy that the first light-emitting device D1 and the second light-emitting device D2 can alternately emit light under the operation of the voltage value of the first power signal VDD and the second power signal VSS. For example, when the voltage value of the first power signal VDD is greater than the second power signal VSS, the first light-emitting device D1 emits light, and the driving current flows from the first power signal VDD to the second power signal VSS. When the voltage value of the first power signal VDD is less than the second power signal VSS, the second light-emitting device D2 emits light, and the driving current flows from the second power signal VSS to the first power signal VDD.
Specifically, please refer to
Wherein, the first high voltage level V1 and the second high voltage level V3 can be any high voltage level that can drive the first light-emitting device D1 and the second light-emitting device D2 to emit light steadily. The levels of the first low voltage level V2 and the second low voltage level V4 can be the levels of the ground terminal. Of course, it is understandable that the levels of the first low voltage level V2 and the second low voltage level V4 may also be other low voltage levels that drive the first light-emitting device D1 and the second light-emitting device D2 to emit light steadily.
In some embodiments of the present disclosure, the first high voltage level V1 and the second high voltage level V3 are the same. The first low voltage level V2 and the second low voltage level V4 are the same. That is, the first power supply signal VDD and the second power supply signal VSS are kept in antiphase at all times. Wherein, keeping the antiphase means that the absolute value of the voltage of the first power signal VDD and the absolute value of the voltage of the second power signal VSS are equal, but the phases are opposite. Therefore, the timing in the light-emitting driving circuit 100 can be simplified, and the power consumption of the power chip that provides the first power signal VDD and the second power signal VSS can be reduced.
Please refer to
The transistors used in all the embodiments of this application can be thin film transistors or field effect transistors or other devices with the same characteristics. Since the source and drain of the transistors used here are symmetrical, the source and drain can be interchangeable. In the embodiments of the present disclosure, in order to distinguish the two electrodes of the transistor except the gate, the first electrode is called the source and the second electrode is called the drain, or the first electrode is called the drain and the second electrode is called the source. According to the structure of the figure, the middle end of the switch transistor is the gate, the signal input end is the source, and the signal output end is the drain. In addition, the transistors used in the embodiments of the present disclosure may include P-type transistors and/or N-type transistors. The P-type transistor is turned on when the gate is at a low voltage level and turned off when the gate is at a high voltage level, and the N-type transistor is turned on when the gate is at a high voltage level and is turned off when the gate is at a low voltage level.
Further, the transistors in the light-emitting driving circuit 100 provided in the present disclosure can be set to be the same type of transistors, so as to avoid the influence of the discrepancies between different types of transistors on the light-emitting driving circuit 100. The following embodiments of the present disclosure are described by taking each transistor as an N-type transistor as an example, but it should not be construed as a limitation of the present disclosure.
Specifically, the switch transistor T1 is turned on when the scan signal Vsc is changed from a low voltage level to a high voltage level, and the data signal Vda is transmitted to the gate of the drive transistor DT through the switch transistor T1 and stored in the storage capacitor Cst. Since the gate level of the drive transistor DT is pulled up to the level of the data signal Vda, the drive transistor DT is turned on. At the same time, when the level of the first power signal VDD is higher than the level of the second power signal VSS, the first power signal VDD, the drive transistor DT, the first light-emitting device D1, and the second power signal VSS form a light-emitting loop. The current flows from the first power signal VDD to the second power signal VSS and the first light-emitting device D1 normally emits light. Conversely, when the level of the first power signal VDD is less than the second power signal VSS, the first power signal VDD, the drive transistor DT, the second light-emitting device D2, and the second power signal VSS form a light-emitting loop. The current flows from the second power signal VSS to the first power signal VDD and the second light-emitting device D2 normally emits light.
Please refer to
In this embodiment, multiple first light-emitting devices D1 and multiple light-emitting devices D2 are provided in the light-emitting module 102, and multiple first light-emitting devices D1 can be arranged in series or in parallel, and multiple second light-emitting devices D2 can be arranged in series or in parallel, which can improve the luminous brightness. And when one of the light-emitting devices fails, the other light-emitting devices can also provide sufficient brightness to further reduce the influence of dead pixels and increase the service life of the light-emitting driving circuit 100.
Please refer to
Specifically, please refer to
The driving timing of the light-emitting driving circuit 100 in this embodiment includes a sensing phase and a light-emitting phase.
In the sensing phase, the scan signal Vsc changes from a low voltage level to a high voltage level, and the switch transistor T1 is turned on. The data signal Vda is transmitted to the gate of the drive transistor DT through the switch transistor T1 and is stored in the storage capacitor Cst. At the same time, the sensing signal Vse is at a high voltage level, and the sensing transistor T2 is turned on, the first switch unit Spre is closed. The reset signal Vref is transmitted to the first electrode of the drive transistor DT, so that the voltage of the first electrode of the drive transistor DT is equal to the reset signal Vref. Then, the scan signal Vsc changes from a high voltage level to a low voltage level, and the switch transistor T1 is cut off, so that the gate of the drive transistor DT is in a floating state. The sensing transistor keeps T2 turned on, and the first switching element Spre is cut off. The voltage of the first electrode of the drive transistor DT rises. When the voltage of one of the source or drain of the drive transistor DT rises until the drive transistor DT is turned off, an external detection source ADC (Analog To Digital Converter) can be used to detect the level of the first electrode of the drive transistor DT, so as to obtain the initial threshold voltage of the drive transistor DT.
In the light-emitting phase, the scan signal Vsc changes from a low voltage level to a high voltage level, the switch transistor T1 is turned on. The data signal Vda is transmitted to the gate of the drive transistor DT through the switch transistor T1 and is stored in the storage capacitor Cst. At the same time, the sensing signal is at a low voltage level, and the sensing transistor T2 is turned off. Since the gate level of the drive transistor DT is pulled up to the level of the data signal Vda, the drive transistor DT is turned on. At the same time, the first light-emitting device D1 or the second light-emitting device D2 emits light, which will not to be repeated here. Among them, the data signal Vda is a signal that has been compensated with a threshold voltage.
In this embodiment, by adding the sensing module 103 to the light-emitting driving circuit 100, the threshold voltage of the drive transistor DT can be detected, thereby realizing a compensation for the threshold voltage drift of the drive transistor DT, and further improving the stability of the drive transistor DT.
It should be noted that the light-emitting driving circuit 100 provided in the present disclosure is only an example, and those skilled in the art can configure the light-emitting driving circuit 100 according to a specific need. That is, the light-emitting driving circuit 100 provided by the embodiment of the present disclosure does not only include the above-described devices. The light-emitting driving circuit 100 provided by the embodiment of the present disclosure may further include other devices. For example, in order to further improve the control of the light-emitting time period of the light-emitting module 102, a transistor can be added between the first power signal VDD and the drive transistor DT, and/or a transistor can be added between the light-emitting module 102 and the second power signal VSS, so as to control the light-emitting time period of the light-emitting module 102. For another example, the light-emitting driving circuit 100 may further include an internal compensation circuit to internally compensate the threshold voltage of the drive transistor DT. Compared with the external detection of the sensing module 103, the internal detection is more convenient.
Please refer to
In the backlight module 200 of the present disclosure, a new type of light-emitting driving circuit 100 is designed. The first power signal and the second power signal are configured to perform level conversion according to a preset period, so that the first light-emitting device and the second light-emitting device emit light alternately. That is, the direction of the current flowing through the drive transistor is changed according to the preset period. Therefore, the current bias of the drive transistor can be effectively improved, the stability of the drive transistor can be improved, such that the backlight module 200 can provide a stable light source.
Please refer to
The display panel 300 may be a mini light-emitting diode (Mini LED) display panel, a micro light-emitting diode (Micro LED) display panel, or an organic light-emitting diode (OLED) display panel.
In the display panel 300 of the present disclosure, a new type of light-emitting driving circuit 100 is designed for the pixel unit 301. The first power signal and the second power signal are configured to perform level conversion according to a preset period, so that the direction of the current flowing through the drive transistor circuit is changed according to the preset period. In this way, the current bias of the drive transistor can be effectively improved, and the stability of the drive transistor can be improved. In turn, the display panel 300 is uniformly displayed and the quality of the display panel 300 can be improved. In addition, the first light-emitting device and the second light-emitting device alternately emit light, which can reduce the influence of dead pixels and improve the quality of the display panel 300.
The embodiments of the present disclosure are described in detail above. Specific examples are used in this article to describe the principles and implementations of the application. The descriptions of the above examples are only used to help understand the methods and core ideas of the application, which do not limit the patent scope of the application. Any equivalent structure or equivalent process transformations derived from the contents of the descriptions and drawings of this application, or directly or indirectly applied in other related technical fields, are similarly included in the patent protection scopes of this application.
Number | Date | Country | Kind |
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202111497201.3 | Dec 2021 | CN | national |
Filing Document | Filing Date | Country | Kind |
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PCT/CN2021/138876 | 12/16/2021 | WO |