CN114283739B - Pixel circuit, driving method thereof and display device - Google Patents
Pixel circuit, driving method thereof and display device Download PDFInfo
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- CN114283739B CN114283739B CN202010982629.6A CN202010982629A CN114283739B CN 114283739 B CN114283739 B CN 114283739B CN 202010982629 A CN202010982629 A CN 202010982629A CN 114283739 B CN114283739 B CN 114283739B
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Abstract
The invention provides a pixel circuit, a driving method thereof and a display device, belongs to the technical field of pixel circuits, and can solve the problem of high power consumption of the existing pixel circuit. The pixel circuit of the present invention includes: a driving sub-circuit and a light emitting device; the driving sub-circuit comprises a driving transistor, and is connected with the first voltage end and the first pole of the light emitting device; the second pole of the light emitting device is connected with a second voltage end; the drive subcircuit is configured to: providing a driving current for the light emitting device in response to the control of the first scanning signal terminal; the number of the second voltage terminals is multiple, and the voltages provided by different second voltage terminals are different; the pixel circuit further includes: the path selection subcircuit is respectively connected with a second pole and a plurality of second voltage terminals of the light-emitting device; the path selection subcircuit is configured to: and responding to the control of the second scanning signal end, and controlling the second pole of the light emitting device to be conducted with the corresponding second voltage end according to the gating control signal.
Description
Technical Field
The invention belongs to the technical field of pixel circuits, and particularly relates to a pixel circuit, a driving method thereof and a display device.
Background
LED light emitting devices are considered as a next generation display panel technology because of their advantages such as ultra-high brightness, long life, and high temperature resistance. The LED display technology may include display technologies such as LEDs, mini LEDs, micro LEDs, etc., and the driving circuit inputs driving current to the corresponding LED display device to achieve light emission.
In the driving circuit, a first pole of the driving transistor is connected with a first voltage end, a second pole of the driving transistor is connected with one end of the LED display device, and a control pole of the driving transistor is connected with an output end of the control unit; the other end of the LED display device is connected with the second voltage end. In the display stage, the driving transistor is conducted under the control of the control unit, and the driving current is written into the LED display device. In Micro/Mini-LED display technology, the pixel driving current is in the mu A (microampere) level, and even reaches the mA level when the display gray level is high. In order to meet the requirements of uA-level and mA-level pixel currents, a driving transistor of a pixel circuit needs to be driven with a larger voltage and works in a saturation region, and in order to meet the Vds voltage requirements of a TFT, the voltage across U of a first voltage end and a second voltage end is larger, so that the overall power consumption of a display substrate is larger.
Disclosure of Invention
The invention aims to at least solve one of the technical problems in the prior art and provide a pixel circuit with lower power consumption.
The technical scheme adopted for solving the technical problem of the invention is a pixel circuit, which comprises: a driving sub-circuit and a light emitting device; the driving sub-circuit comprises a driving transistor, and is connected with a first voltage end and a first pole of the light emitting device; the second pole of the light emitting device is connected with a second voltage end; the drive subcircuit is configured to: providing a driving current for the light emitting device in response to the control of the first scanning signal terminal; it is characterized in that the method comprises the steps of,
the number of the second voltage terminals is multiple, and the voltages provided by different second voltage terminals are different;
the pixel circuit further includes: a path selection sub-circuit connected to a second pole of the light emitting device and the plurality of second voltage terminals, respectively;
the path selection subcircuit is configured to: and responding to the control of the second scanning signal end, and controlling the second pole of the light emitting device to be conducted with the corresponding second voltage end according to the gating control signal of the gating control signal end.
Optionally, the number of second voltage terminals includes two.
Further optionally, the two second voltage terminals include a first negative voltage terminal and a second negative voltage terminal;
the path selection sub-circuit comprises a first gating control unit, a second gating control unit, a first gating transistor and a second gating transistor;
the control electrode of the first gating transistor is connected with the output end of the first gating control unit; the first electrode is connected with the second electrode of the light-emitting unit, and the second electrode is connected with the first negative pressure end;
the control electrode of the second gating transistor is connected with the output end of the second gating control unit; the first electrode is connected with a second electrode of the light-emitting unit, and the second electrode is connected with the second negative pressure end;
the first gating control unit is configured to: writing a first gating control signal into a control electrode of a first gating transistor in response to control of a second scanning signal end so as to enable the first gating transistor to be turned on or turned off;
the second gating control unit is configured to: and responding to the control of the second scanning signal end, writing a second gating control signal into the control electrode of the second gating transistor so as to enable the second gating transistor to be turned on or turned off.
Further optionally, the first gating control unit includes: a first gate transistor and a first gate capacitor; the control electrode of the first gating control transistor is connected with the second scanning signal, the first electrode is connected with the control electrode of the first gating transistor, and the second electrode is connected with the gating control signal end; one pole of the first gating capacitor is connected with the control pole of the first gating transistor, and the other pole of the first gating capacitor is connected with the common voltage end;
the second gating control unit includes: a second gate control transistor and a second gate capacitor; the control electrode of the second gating control transistor is connected with the second scanning signal, the first electrode is connected with the control electrode of the second gating transistor, and the second electrode is connected with the gating control signal end; one pole of the second gating capacitor is connected with the control pole of the second gating transistor, and the other pole of the second gating capacitor is connected with the common voltage end.
Optionally, the two second voltage ends include a first negative voltage end and a second negative voltage end;
the path selection sub-circuit comprises a first gating control unit, a first gating transistor and a second gating transistor; the first gating transistor and the second gating transistor have opposite electrical characteristics;
a first pole of the first gating transistor is connected with a second pole of the light emitting unit, and the second pole is connected with the first negative voltage end;
the first pole of the second gating transistor is connected with the second pole of the light emitting unit, and the second pole is connected with the second negative voltage end;
the control electrode of the first gating transistor and the control electrode of the second gating transistor are connected with the output end of the first gating control unit at a gating node;
the first gating control unit is configured to: and responding to the control of the second scanning signal end, writing a first gating control signal into the gating node so as to enable the first gating transistor or the second gating transistor to be conducted.
Further optionally, the first gating control unit includes: a first gate control transistor and a first gate capacitor;
the control electrode of the first gating control transistor is connected with the second scanning signal end, the first electrode is connected with the gating node, and the second electrode is connected with the first gating control signal end;
one pole of the first gating capacitor is connected with the gating node, and the other pole of the first gating capacitor is connected with the common voltage end.
Optionally, the driving sub-circuit includes: a data writing transistor, a driving transistor and a storage capacitor; the control electrode of the data writing transistor is connected with a first scanning signal end, the first electrode is connected with a data signal end, and the second electrode is connected with the control electrode of the driving transistor and one electrode of the storage capacitor at a first node;
a first electrode of the driving transistor is connected with a first voltage end, and a second electrode of the driving transistor is connected with a first electrode of the light emitting device;
the other pole of the storage capacitor is connected with the first voltage end.
Optionally, the pixel circuit further comprises a threshold compensation sub-circuit; the threshold compensation sub-circuit includes: a reset transistor, a threshold compensation transistor, a first light emission control transistor, and a second light emission control transistor;
the driving sub-circuit includes: a data writing transistor, a driving transistor and a storage capacitor; the control electrode of the data writing transistor is connected with a first scanning signal end, the first electrode is connected with a data signal end, and the second electrode is connected with the first electrode of the driving transistor and the second electrode of the first light emitting control transistor; the first electrode of the first light-emitting control transistor is connected with a first voltage end, and the control electrode is connected with a light-emitting control voltage end; one pole of the storage capacitor is connected with the first voltage end, and the other pole of the storage capacitor is connected with the control pole of the driving transistor, the first pole of the reset transistor and the first pole of the threshold compensation transistor;
the second electrode of the driving transistor is connected with the first electrode of the light emitting device, the second electrode of the threshold compensation transistor and the first electrode of the second light emitting control transistor;
the control electrode of the threshold compensation transistor is connected with the first scanning signal end;
the control electrode of the second light-emitting control transistor is connected with the light-emitting control signal end, and the second electrode is connected with the first electrode of the light-emitting device.
Another technical solution adopted to solve the technical problem of the present invention is a display device, including any one of the above pixel circuits.
Another technical solution adopted to solve the technical problem of the present invention is a driving method applied to any one of the above pixel circuits, the driving method comprising:
writing effective levels into the first scanning signal end and the second scanning signal end so as to enable a gating control signal of the gating control signal end to be written into a channel selection sub-circuit and control the second pole of the light emitting device to be conducted with the corresponding second voltage end;
the gate control signal is related to a numerical range of display gray scales of the light emitting device.
Drawings
FIG. 1 is a schematic diagram of a pixel circuit according to an embodiment of the invention;
FIG. 2 is a timing diagram of signals of the pixel circuit of FIG. 1 during high gray scale display;
FIG. 3 is a timing diagram of signals of the pixel circuit of FIG. 1 during low gray scale display;
FIG. 4 is a schematic diagram of another pixel circuit according to an embodiment of the invention;
FIG. 5 is a timing diagram of signals of the pixel circuit of FIG. 4 in a high gray scale display;
FIG. 6 is a timing diagram of signals of the pixel circuit provided in FIG. 4 during low gray scale display;
FIG. 7 is a schematic diagram of another pixel circuit according to an embodiment of the invention;
FIG. 8 is a timing diagram of signals of the pixel circuit provided in FIG. 7 during high gray scale display;
fig. 9 is a signal timing diagram of the pixel circuit provided in fig. 7 at the time of low gray scale display.
Detailed Description
The present invention will be described in further detail below with reference to the drawings and detailed description for the purpose of better understanding of the technical solution of the present invention to those skilled in the art. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
Unless defined otherwise, technical or scientific terms used in the embodiments of the present invention should be given the ordinary meaning as understood by one of ordinary skill in the art to which the present invention belongs. The terms "first," "second," and the like, as used herein, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Likewise, the word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, which may also be changed when the absolute position of the object to be described is changed.
Example 1:
as shown in fig. 1 to 3, the present embodiment provides a pixel circuit including: a driving sub-circuit and a light emitting device D; the driving sub-circuit comprises a driving transistor T2, and is connected with a first voltage end VDD and a first pole of the light emitting device D; the second pole of the light emitting device D is connected with a second voltage end; the drive subcircuit is configured to: the driving current is supplied to the light emitting device D in response to the control of the first scan signal terminal gate_a. The light emitting device D is a current driven light emitting device D, and specifically may be an LED (Light Emitting Diode; light emitting diode), mini LED, micro LED, etc. The display gray scale of the light emitting device D is related to the driving current inputted thereto by the driving sub-circuit. The display power consumption of the pixel circuit is related to the voltage difference (cross voltage) between the first voltage terminal VDD and the second voltage terminal, and the driving current. The display gray scale of the light emitting device D is different, the driving current is different, and the display power consumption of the pixel circuit is also different. The voltage difference between the first voltage terminal VDD and the second voltage terminal should satisfy the driving voltage of the driving transistor T2, so as to ensure that the driving transistor T2 works in the saturation region. The larger the drive current, the larger the required drive voltage and therefore the larger the need for a voltage across. In the prior art, in order to ensure that a driving current corresponding to each display gray level can be input to the light emitting device D in the driving sub-circuit, a constant value of a voltage is generally large so as to be able to satisfy a driving current of any display gray level including a maximum display gray level. But such an arrangement results in a larger power consumption of the pixel circuit. Particularly, in the embodiment, the number of the second voltage terminals is plural, and the voltages provided by different second voltage terminals are different; meanwhile, the pixel circuit further includes: the path selection subcircuit is respectively connected with a second pole and a plurality of second voltage ends of the light-emitting device D; the path selection subcircuit is configured to: and responding to the control of the second scanning signal terminal gate_b, and controlling the second pole of the light emitting device D to be conducted with the corresponding second voltage terminal according to the gating control signal of the gating control signal terminal.
One of the first voltage terminal VDD and the second voltage terminal is a high voltage terminal, and the other is a low voltage terminal. The first voltage terminal VDD is a voltage source for outputting a constant first voltage, and the first voltage is a positive voltage; the second voltage terminal may be a voltage source to output a constant second voltage, and the second voltage may be a negative voltage. In this embodiment, the first voltage terminal VDD is a positive voltage, and the second voltage terminal VDD is a negative voltage.
In the pixel circuit provided in this embodiment, a plurality of second voltage terminals providing different voltage values are provided, and the channel is selected by using the channel selection sub-circuit, so that the first voltage terminal VDD can be conducted with different second voltage terminals when the pixel circuit displays different display gray scales. Based on the pixel circuit provided in this embodiment, voltages of different second voltage terminals may be set corresponding to the display gray levels when the display is performed, and the corresponding second voltage terminal may be selected to be turned on when the display gray levels are different. When the voltage of the second voltage terminal is set, the voltage crossing voltage between the second voltage terminal and the first voltage terminal VDD can meet the driving voltage requirement of the corresponding display gray scale. Therefore, in this embodiment, the voltage across the first voltage terminal VDD and the second voltage terminal does not always need to meet the maximum display gray level, and when the gray level is displayed at a lower level, the voltage across can be relatively reduced, so that the overall display power consumption of the pixel circuit can be reduced, and low-power display can be realized.
Optionally, in this embodiment, the number of the second voltage terminals is two. In the prior art, the conventional display gray scale of the pixel circuit generally has 255 levels, and the number of the display gray scale levels is large. The second voltage terminal is arranged corresponding to each display gray level, which results in too complex pixel circuit structure and has certain difficulty for the actual production of the pixel circuit. In the pixel circuit of this embodiment, two second voltage terminals may be preferably disposed, corresponding to two different ranges of display gray scales, one higher and one lower. When the high gray scale display is performed, the second pole of the light emitting device D is conducted with one of the second voltage ends, and at the moment, the voltage across the first voltage end VDD and the second voltage end is U0; when the gray scale is low, the second pole of the light emitting device D is turned on with another second voltage terminal, and the voltage across the first voltage terminal VDD and the second voltage terminal is U1. The voltage across U1 is required to meet the low-gray-scale low-current driving voltage, so U1 is smaller than U0. Assuming that the total pixel current is I0 and the total pixel current is I1 in the low-gray-scale display, the power consumption of the pixel circuit is U0×i0 in the high-gray-scale display, and U1×i1 in the low-gray-scale display, compared with the prior art, the power consumption of the pixel circuit is U0×i1 in the low-gray-scale display, and the display power consumption of the pixel circuit in the low-gray-scale display is lower, so that the display power consumption of the pixel circuit can be obviously reduced.
In order to more clearly describe the pixel circuit provided in this embodiment, the following description will be made with the number of the second voltage terminals being two. Of course, it is understood that, in the pixel circuit, a plurality of second voltage terminals, such as three, four, etc., may be provided, corresponding to different ranges of display gray scales, which is not limited in this embodiment.
As shown in fig. 1, in the present embodiment, the two second voltage terminals include a first negative voltage terminal VSS0 and a second negative voltage terminal VSS1; the path selection sub-circuit comprises a first gating control unit, a second gating control unit, a first gating transistor T3 and a second gating transistor T4; the control electrode of the first gating transistor T3 is connected with the output end of the first gating control unit; the first electrode is connected with a second electrode of the light-emitting unit, and the second electrode is connected with a first negative pressure end VSS 0; the control electrode of the second gating transistor T4 is connected with the output end of the second gating control unit; the first pole is connected with the second pole of the light emitting unit, and the second pole is connected with the second negative voltage end VSS1.
The first gating control unit is configured to: writing a first gating control signal into a control electrode of the first gating transistor T3 in response to control of the second scanning signal terminal gate_B so as to enable the first gating transistor T3 to be turned on or turned off; the second gating control unit is configured to: in response to the control of the second scan signal terminal gate_b, a second Gate control signal is written to the control electrode of the second Gate transistor T4 to turn on or off the second Gate transistor T4.
Optionally, the first gating control unit includes: a first gate transistor T3 and a first gate capacitor C2; the control electrode of the first gating control transistor T5 is connected with a second scanning signal, the first electrode is connected with the control electrode of the first gating transistor T3, and the second electrode is connected with the gating control signal end data_T1; one pole of the first gating capacitor C2 is connected to the control pole of the first gating transistor T3, and the other pole is connected to the common voltage terminal VCOM.
The second gating control unit includes: a second gate control transistor T6 and a second gate capacitor C3; the control electrode of the second gating control transistor T6 is connected with a second scanning signal, the first electrode is connected with the control electrode of the second gating transistor T4, and the second electrode is connected with the gating control signal end data_T1; one pole of the second gating capacitor C3 is connected to the control pole of the second gating transistor T4, and the other pole is connected to the common voltage terminal VCOM.
Alternatively, as shown in fig. 1, the driving sub-circuit includes: a data writing transistor T1, a driving transistor T2, and a storage capacitor C1; the control electrode of the Data writing transistor T1 is connected with a first scanning signal end gate_A, the first electrode is connected with a Data signal end data_I, and the second electrode is connected with the control electrode of the driving transistor T2 and one electrode of the storage capacitor C1; a first pole of the driving transistor T2 is connected to the first voltage terminal VDD, and a second pole is connected to the first pole of the light emitting device D; the other pole of the storage capacitor C1 is connected to the first voltage terminal VDD.
In this embodiment, the first scan signal and the second scan signal may be the same, that is, the control electrode of the data writing transistor T1 and the control electrode of the gate control transistor may be electrically connected to the same signal line, receive the same signal, and reduce the number of signal lines. For another example, the control electrode of the data writing transistor T1 and the control electrode of the gate control transistor may be electrically connected to different signal lines, respectively, and may receive the same signal.
It should be noted that the first scan signal, the second scan signal, and the compensation control signal may be different, so that the data writing transistor T1 and the gate control transistor may be separately and individually controlled, thereby increasing flexibility of controlling the pixel circuit.
In the present embodiment, at the time of displaying, one of the first gate transistor T3 and the second gate transistor T4 is selected to be turned on by the control of the first gate control unit and the second gate control unit according to the difference in display gray scale. The first gating transistor T3 and the second gating transistor T4 are controlled by the first gating control unit and the second gating control unit respectively, so that the electrical characteristics of the first gating transistor T3 and the second gating transistor T4 can be the same or opposite.
The driving process of the pixel circuit of the present embodiment is explained below with reference to fig. 1 to 3. The first and second gate transistors T3 and T4 are P-type transistors, which are illustrated by taking the voltage of the first negative voltage terminal VSS0 being lower than the voltage of the second negative voltage terminal VSS1.
At the time of high gray scale display, as shown in fig. 1 and 2, an active level signal is supplied to the first scanning terminal and the second scanning terminal. The Data writing transistor T1 writes the Data signal provided by the Data signal end data_I into the control electrode of the driving transistor T2, the driving transistor T2 is conducted, and a large driving current is provided for the light emitting device D so as to meet the high gray scale display requirement; meanwhile, in order to meet the requirement of larger current driving, the first gating control transistor T5 writes a first gating control signal (low level signal) provided by the first gating control signal terminal data_t1 into the first gating transistor T3, and controls the first gating transistor T3 to be turned on, so that the second pole of the light emitting device D is turned on with the first negative voltage terminal VSS0, and larger voltage across between the first voltage terminal VDD and the second voltage terminal is realized; the second gate control transistor T6 writes a second gate control signal (high level signal) provided by the second gate control signal terminal data_t2 into the second gate transistor T4, and controls the second gate transistor T4 to be turned off.
At the time of low gray scale display, as shown in fig. 1 and 3, an active level signal is supplied to the first scanning terminal and the second scanning terminal. The Data writing transistor T1 writes the Data signal provided by the Data signal terminal data_I into the control electrode of the driving transistor T2, the driving transistor T2 is conducted, and driving current is provided for the light emitting device D, so long as the low gray scale display requirement can be met; the first gating control transistor T5 writes a first gating control signal (high level signal) provided by the first gating control signal terminal data_t1 into the first gating transistor T3, and controls the first gating transistor T3 to be turned off; the second gate control transistor T6 writes a second gate control signal (low level signal) provided by the second gate control signal terminal data_t2 into the second gate transistor T4, and controls the second gate transistor T4 to be turned on, so that the second electrode of the light emitting device D is turned on with the second negative voltage terminal VSS1, and a voltage across the first voltage terminal VDD and the second voltage terminal is relatively small.
Example 2:
as shown in fig. 4 to 9, the present embodiment provides a pixel circuit similar to that provided in embodiment 1, including a driving sub-circuit, a light emitting device D, a path selecting sub-circuit, and the like. The number of the second voltage terminals is also two, and the second voltage terminals are respectively a first negative voltage terminal VSS0 and a second negative voltage terminal VSS1. In particular, in the present embodiment, the number of gate control units is one.
Specifically, as shown in fig. 4 and 7, in the present embodiment, the path selection sub-circuit includes a first gate control unit, a first gate transistor T3, and a second gate transistor T4; the first gating transistor T3 has opposite electrical characteristics to the second gating transistor T4; a first pole of the first gating transistor T3 is connected with a second pole of the light emitting unit, and the second pole is connected with a first negative voltage end VSS 0; the first pole of the second gating transistor T4 is connected with the second pole of the light emitting unit, and the second pole is connected with the second negative voltage end VSS1; the control electrode of the first gating transistor T3 and the control electrode of the second gating transistor T4 are connected with the output end of the first gating control unit to be connected with the gating node.
The first gating control unit is configured to: in response to the control of the second scan signal terminal gate_b, a first Gate control signal is written to the Gate node N2 to turn on the first Gate transistor T3 or the second Gate transistor T4.
Optionally, in this embodiment, the first gating control unit includes: a first gate control transistor T5 and a first gate capacitor C2; the control electrode of the first gating control transistor T5 is connected with a second scanning signal end gate_B, the first electrode is connected with a gating node N2, and the second electrode is connected with a first gating control signal end data_T1; one pole of the first gating capacitor C2 is connected to the gating node N2, and the other pole is connected to the common voltage terminal VCOM.
In this embodiment, based on the gating transistors with different electrical characteristics, when displaying, according to the difference of the display gray scale, the first gating control signal can be written into the gating node N2 in response to the second scanning signal, and at the same time, the first gating transistor T3 and the second gating transistor T4 are controlled to be turned on, so that one of them is turned off.
As an embodiment, as shown in fig. 4, the driving sub-circuit includes: a data writing transistor T1, a driving transistor T2, and a storage capacitor C1; the control electrode of the Data writing transistor T1 is connected with a first scanning signal end gate_A, the first electrode is connected with a Data signal end data_I, and the second electrode is connected with the control electrode of the driving transistor T2 and one electrode of the storage capacitor C1; a first pole of the driving transistor T2 is connected to the first voltage terminal VDD, and a second pole is connected to the first pole of the light emitting device D; the other pole of the storage capacitor C1 is connected to the first voltage terminal VDD.
The driving process of the pixel circuit of the present embodiment will be explained below with reference to fig. 4 to 6. The first gating transistor T3 is a P-type transistor, and the second gating transistor T4 is an N-type transistor, which is illustrated by taking the voltage of the first negative voltage terminal VSS0 being lower than the voltage of the second negative voltage terminal VSS1 as an example.
At the time of high gray scale display, as shown in fig. 4 and 5, an active level signal is supplied to the first scanning terminal and the second scanning terminal. The Data writing transistor T1 writes the Data signal provided by the Data signal end data_I into the control electrode of the driving transistor T2, the driving transistor T2 is conducted, and a large driving current is provided for the light emitting device D so as to meet the high gray scale display requirement; meanwhile, in order to meet the requirement of larger current driving, the first gating control transistor T5 writes a first gating control signal (low level signal) provided by the first gating control signal terminal data_t1 into the first gating transistor T3, and controls the first gating transistor T3 to be turned on, so that the second pole of the light emitting device D is turned on with the first negative voltage terminal VSS0, and larger voltage across between the first voltage terminal VDD and the second voltage terminal is realized; meanwhile, since the second gating transistor T4 has opposite electrical characteristics to the first gating transistor T3, it is turned off under the control of the first gating control signal.
At the time of low gray scale display, as shown in fig. 4 and 6, an active level signal is supplied to the first scanning terminal and the second scanning terminal. The Data writing transistor T1 writes the Data signal provided by the Data signal terminal data_I into the control electrode of the driving transistor T2, the driving transistor T2 is conducted, a small driving current is provided for the light emitting device D, and gray scale display requirements can be met; meanwhile, the first gating control transistor T5 writes the first gating control signal (high level signal) provided by the first gating control signal terminal data_t1 into the first gating transistor T3, and controls the first gating transistor T3 to be turned off; meanwhile, since the second gate transistor T4 is turned on, the second negative voltage terminal VSS1 is turned on with the second diode of the light emitting device D.
As another implementation manner, as shown in fig. 7, the pixel circuit provided in this embodiment further includes a threshold compensation sub-circuit; the threshold compensation sub-circuit includes: a reset transistor T8, a threshold compensation transistor T7, a first light emission control transistor T9, and a second light emission control transistor T10; the driving sub-circuit includes: a data writing transistor T1, a driving transistor T2, and a storage capacitor C1; the control electrode of the Data writing transistor T1 is connected with a first scanning signal end gate_A, the first electrode is connected with a Data signal end data_I, and the second electrode is connected with the first electrode of the driving transistor T2 and the second electrode of the first light emitting control transistor T9; a first electrode of the first light emitting control transistor T9 is connected with a first voltage end VDD, and a control electrode is connected with a light emitting control voltage end; one pole of the storage capacitor C1 is connected with the first voltage end VDD, and the other pole is connected with the control pole of the driving transistor T2, the first pole of the reset transistor T8 and the first pole of the threshold compensation transistor T7; the second electrode of the driving transistor T2 is connected with the first electrode of the light emitting device D, the second electrode of the threshold compensation transistor T7 and the first electrode of the second light emission control transistor T10; the control electrode of the threshold compensation transistor T7 is connected with the first scanning signal end gate_A; the control electrode of the second light emission control transistor T10 is connected to the light emission control signal terminal EM, and the second electrode is connected to the first electrode of the light emitting device D.
In this embodiment, the first scan signal, the second scan signal, and the compensation control signal may be the same, i.e., the control electrode of the data writing transistor T1, the gate control transistor, and the control electrode of the threshold compensation transistor T7 may be electrically connected to the same signal line to reduce the number of signal lines. For another example, the control electrode of the data writing transistor T1 and the control electrode of the threshold compensating transistor T7 may be electrically connected to different signal lines, respectively, but the transmitted signals are the same.
It should be noted that the first scan signal, the second scan signal, and the compensation control signal may be different, so that the data writing transistor T1, the first gate control transistor T5, and the threshold compensation transistor T7 may be separately and individually controlled, thereby increasing flexibility of controlling the pixel circuit. In the embodiment of the present disclosure, the control electrode of the data writing transistor T1 and the control electrode of the threshold compensating transistor T7 are connected to the first scan signal terminal gate_a.
Likewise, the first light emission control signal and the second light emission control signal may be the same, i.e., the control electrode of the first light emission control transistor T9 and the control electrode of the second light emission control transistor T10 may be electrically connected to the same signal line, and the control electrode of the first light emission control transistor T9 and the control electrode of the second light emission control transistor T10 may be electrically connected to different signal lines, respectively, but transmitted signals are the same.
It should be noted that, when the first light emitting control transistor T9 and the second light emitting control transistor T10 are different types of transistors, for example, the first light emitting control transistor T9 is a P-type transistor, and the second light emitting control transistor T10 is an N-type transistor, the first light emitting control signal and the second light emitting control signal may also be different, which is not limited in this embodiment of the present disclosure. In the embodiment of the present disclosure, the control electrodes of the first light emission control transistor T9 and the second light emission control transistor T10 are both connected to the light emission control signal terminal EM.
The driving process of the pixel circuit of the present embodiment will be explained below with reference to fig. 7 to 9. The first gating transistor T3 is a P-type transistor, and the second gating transistor T4 is an N-type transistor, which is illustrated by taking the voltage of the first negative voltage terminal VSS0 being lower than the voltage of the second negative voltage terminal VSS1 as an example.
In the reset phase, an active level signal is supplied to the reset signal terminal RST, and the first node N1 is reset to a corresponding initial voltage.
In the Data writing stage, an effective level signal is provided for a first scanning signal end gate_A and a second scanning signal end gate_B, a Data writing transistor T1 is conducted, and a Data signal provided by a Data signal end data_I is written into a first pole of a driving transistor T2; at the same time, the threshold compensation transistor T7 is turned on, and the threshold compensation voltage is written into the control electrode of the driving transistor T2. In the high gray scale display, as shown in fig. 7 and 8, in order to be able to meet the requirement of larger current driving, the first gate control transistor T5 writes the first gate control signal (low level signal) provided by the first gate control signal terminal data_t1 into the first gate transistor T3, and controls the first gate transistor T3 to be turned on, so that the second pole of the light emitting device D is turned on with the first negative voltage terminal VSS0, and a larger voltage across the first voltage terminal VDD and the second voltage terminal is realized; meanwhile, since the second gating transistor T4 has opposite electrical characteristics to the first gating transistor T3, it is turned off under the control of the first gating control signal. In the low gray scale display, as shown in fig. 7 and 9, the driving transistor T2 provides a smaller driving current for the light emitting device D, so that the gray scale display requirement is satisfied; the first gating control transistor T5 writes a first gating control signal (high level signal) provided by the first gating control signal terminal data_t1 into the first gating transistor T3, and controls the first gating transistor T3 to be turned off; meanwhile, since the second gate transistor T4 is turned on, the second negative voltage terminal VSS1 is turned on with the second diode of the light emitting device D.
In the light emitting stage, an effective level signal is written into the light emitting control signal terminal EM, the first light emitting control transistor T9 and the second light emitting control transistor T10 are turned on, a first voltage signal of the first voltage terminal VDD is written into the first pole of the driving transistor T2, the driving transistor T2 is turned on, and a driving current is written into the light emitting device D.
Example 3:
the present embodiment provides a display device including any one of the pixel circuits provided in embodiment 1.
The display device may be: electronic paper, OLED panel, mobile phone, tablet computer, television, display, notebook computer, digital photo frame, navigator, etc. Other essential components of the display device will be understood by those skilled in the art, and are not described herein in detail, nor should they be considered as limiting the invention.
Example 4:
the present embodiment provides a driving method applied to any one of the pixel circuits provided in embodiment 1 or embodiment 2, the driving method including:
writing effective levels into the first scanning signal end and the second scanning signal end so as to enable a gating control signal of the gating control signal end to be written into the channel selection sub-circuit and control the second pole of the light emitting device to be conducted with the corresponding second voltage end; wherein the gate control signal is related to a numerical range of display gray scale of the light emitting device.
One of the first voltage terminal and the second voltage terminal is a high voltage terminal, and the other is a low voltage terminal. The first voltage end is a voltage source for outputting constant first voltage, and the first voltage is a positive voltage; the second voltage terminal may be a voltage source to output a constant second voltage, the second voltage being a negative voltage, etc. For example, the second voltage terminal VSS may be grounded. In this embodiment, the first voltage terminal is a positive voltage, and the second voltage terminal is a negative voltage.
Alternatively, in this embodiment, the number of the second voltage terminals VSS may be two, which are the first negative voltage terminal and the second negative voltage terminal, respectively. The first and second gate transistors are P-type transistors, for example, where the voltage at the first negative voltage terminal is lower than the voltage at the second negative voltage terminal. The driving method specifically may include:
and in the high gray scale display, providing an effective level signal to the first scanning end and the second scanning end. The data writing transistor writes the data signal provided by the data signal end into the control electrode of the driving transistor, the driving transistor is conducted, and a large driving current is provided for the light emitting device so as to meet the high gray scale display requirement; meanwhile, in order to meet the requirement of larger current driving, the gating control unit writes gating control signals into the first gating transistor and the second gating transistor, controls the first gating transistor to be turned on, and turns off the second gating transistor so as to enable the second pole of the light emitting device to be turned on with the first negative voltage end, and realizes larger voltage across between the first voltage end and the second voltage end.
And providing an effective level signal to the first scanning end and the second scanning end during low gray scale display. The data writing transistor writes the data signal provided by the data signal end into the control electrode of the driving transistor, the driving transistor is conducted, and driving current is provided for the light emitting device, so long as the low gray scale display requirement can be met; the gating control unit writes gating control signals into the first gating transistor and the second gating transistor, controls the first gating transistor to be turned off, and the second gating transistor to be turned on so as to enable the second pole of the light emitting device to be turned on with the second negative voltage end, and the voltage between the first voltage end and the second voltage end is relatively smaller.
In the driving method of the pixel circuit provided in this embodiment, when different display gray scales are displayed, the connection paths of the second voltage terminals of the pair of path selection sub-circuits are used to select, so that the first voltage terminal VDD can be conducted with the different second voltage terminals. Specifically, voltages of different second voltage terminals can be set corresponding to different display gray scales, and the corresponding second voltage terminal is selected to be conducted when different display gray scales are displayed. When the voltage of the second voltage terminal is set, the voltage crossing voltage between the second voltage terminal and the first voltage terminal VDD can meet the driving voltage requirement of the corresponding display gray scale. In the driving method, the voltage across the first voltage end VDD and the second voltage end does not need to meet the maximum display gray level, and the voltage across the first voltage end VDD and the second voltage end does not need to meet the maximum display gray level, so that the voltage across the second voltage end VDD and the second voltage end does not need to meet the maximum display gray level, and the voltage across the first voltage end VDD and the second voltage end VDD can be relatively reduced when the gray level is displayed, thereby reducing the overall display power consumption of the pixel circuit and realizing low-power display.
It is to be understood that the above embodiments are merely illustrative of the application of the principles of the present invention, but not in limitation thereof. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the invention, and are also considered to be within the scope of the invention.
Claims (10)
1. A pixel circuit, comprising: a driving sub-circuit and a light emitting device; the driving sub-circuit comprises a driving transistor, and is connected with a first voltage end and a first pole of the light emitting device; the second pole of the light emitting device is connected with a second voltage end; the drive subcircuit is configured to: providing a driving current for the light emitting device in response to the control of the first scanning signal terminal; it is characterized in that the method comprises the steps of,
the number of the second voltage terminals is multiple, and the voltages provided by different second voltage terminals are different;
the pixel circuit further includes: a path selection sub-circuit connected to a second pole of the light emitting device and the plurality of second voltage terminals, respectively;
the path selection subcircuit is configured to: responding to the control of a second scanning signal end, and enabling the first voltage end to be conducted with different second voltage ends when the pixel circuit displays different display gray scales according to the gating control signal of the gating control signal end; the voltage across the second voltage end and the first voltage end can meet the driving voltage requirement of corresponding display gray scale.
2. The pixel circuit of claim 1, wherein the number of second voltage terminals comprises two.
3. The pixel circuit of claim 2, wherein the two second voltage terminals comprise a first negative voltage terminal and a second negative voltage terminal;
the path selection sub-circuit comprises a first gating control unit, a second gating control unit, a first gating transistor and a second gating transistor;
the control electrode of the first gating transistor is connected with the output end of the first gating control unit; the first electrode is connected with the second electrode of the light-emitting device, and the second electrode is connected with the first negative voltage end;
the control electrode of the second gating transistor is connected with the output end of the second gating control unit; the first electrode is connected with a second electrode of the light-emitting device, and the second electrode is connected with the second negative voltage end;
the first gating control unit is configured to: writing a first gating control signal into a control electrode of a first gating transistor in response to control of a second scanning signal end so as to enable the first gating transistor to be turned on or turned off;
the second gating control unit is configured to: and responding to the control of the second scanning signal end, writing a second gating control signal into the control electrode of the second gating transistor so as to enable the second gating transistor to be turned on or turned off.
4. A pixel circuit according to claim 3, wherein the first gate control unit comprises: a first gate control transistor and a first gate capacitor; the control electrode of the first gating control transistor is connected with the second scanning signal, the first electrode is connected with the control electrode of the first gating transistor, and the second electrode is connected with the gating control signal end; one pole of the first gating capacitor is connected with the control pole of the first gating transistor, and the other pole of the first gating capacitor is connected with the common voltage end;
the second gating control unit includes: a second gate control transistor and a second gate capacitor; the control electrode of the second gating control transistor is connected with the second scanning signal, the first electrode is connected with the control electrode of the second gating transistor, and the second electrode is connected with the gating control signal end; one pole of the second gating capacitor is connected with the control pole of the second gating transistor, and the other pole of the second gating capacitor is connected with the common voltage end.
5. The pixel circuit of claim 2, wherein the two second voltage terminals comprise a first negative voltage terminal and a second negative voltage terminal;
the path selection sub-circuit comprises a first gating control unit, a first gating transistor and a second gating transistor; the first gating transistor and the second gating transistor have opposite electrical characteristics;
a first pole of the first gating transistor is connected with a second pole of the light emitting device, and the second pole is connected with the first negative voltage end;
the first pole of the second gating transistor is connected with the second pole of the light emitting device, and the second pole is connected with the second negative voltage end;
the control electrode of the first gating transistor and the control electrode of the second gating transistor are connected with the output end of the first gating control unit at a gating node;
the first gating control unit is configured to: and responding to the control of the second scanning signal end, writing a first gating control signal into the gating node so as to enable the first gating transistor or the second gating transistor to be conducted.
6. The pixel circuit according to claim 5, wherein the first gate control unit includes: a first gate control transistor and a first gate capacitor;
the control electrode of the first gating control transistor is connected with the second scanning signal end, the first electrode is connected with the gating node, and the second electrode is connected with the first gating control signal end;
one pole of the first gating capacitor is connected with the gating node, and the other pole of the first gating capacitor is connected with the common voltage end.
7. The pixel circuit of claim 1, wherein the drive sub-circuit comprises: a data writing transistor, a driving transistor and a storage capacitor; the control electrode of the data writing transistor is connected with a first scanning signal end, the first electrode is connected with a data signal end, and the second electrode is connected with the control electrode of the driving transistor and one electrode of the storage capacitor at a first node;
a first electrode of the driving transistor is connected with a first voltage end, and a second electrode of the driving transistor is connected with a first electrode of the light emitting device;
the other pole of the storage capacitor is connected with the first voltage end.
8. The pixel circuit of claim 1, further comprising a threshold compensation sub-circuit; the threshold compensation sub-circuit includes: a reset transistor, a threshold compensation transistor, a first light emission control transistor, and a second light emission control transistor;
the driving sub-circuit includes: a data writing transistor, a driving transistor and a storage capacitor; the control electrode of the data writing transistor is connected with a first scanning signal end, the first electrode is connected with a data signal end, and the second electrode is connected with the first electrode of the driving transistor and the second electrode of the first light emitting control transistor; the first electrode of the first light-emitting control transistor is connected with a first voltage end, and the control electrode is connected with a light-emitting control voltage end; one pole of the storage capacitor is connected with the first voltage end, and the other pole of the storage capacitor is connected with the control pole of the driving transistor, the first pole of the reset transistor and the first pole of the threshold compensation transistor;
the second electrode of the driving transistor is connected with the first electrode of the light emitting device, the second electrode of the threshold compensation transistor and the first electrode of the second light emitting control transistor;
the control electrode of the threshold compensation transistor is connected with the first scanning signal end;
the control electrode of the second light-emitting control transistor is connected with the light-emitting control signal end, and the second electrode is connected with the first electrode of the light-emitting device.
9. A display device comprising the pixel circuit according to any one of claims 1 to 8.
10. A driving method applied to the pixel circuit according to any one of claims 1 to 8, characterized by comprising:
writing effective levels into the first scanning signal end and the second scanning signal end so as to enable a gating control signal of the gating control signal end to be written into a channel selection sub-circuit and control the second pole of the light emitting device to be conducted with the corresponding second voltage end;
the gate control signal is related to a numerical range of display gray scales of the light emitting device.
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