CN111462699B - Pixel circuit, driving method thereof and display device - Google Patents
Pixel circuit, driving method thereof and display device Download PDFInfo
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- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
- G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
- G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
- G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
- G09G3/3225—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
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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 that the brightness improvement range of the conventional OLED display module is limited. The pixel circuit comprises a drive sub-circuit, a light-emitting sub-circuit and a control sub-circuit, wherein the drive sub-circuit is configured to respond to the control of a scanning end and output a drive voltage to drive the light-emitting sub-circuit to emit light; the first end of the voltage regulation subcircuit and the output end of the driving subcircuit are connected to a first node, and the second end of the voltage regulation subcircuit and the first end of the light-emitting subcircuit are connected to a second node; the voltage regulation subcircuit is configured to: responding to the control of a first control voltage end, carrying out voltage regulation on the voltage of the first node, and transmitting the regulated driving voltage to the second node so as to drive the light-emitting sub-circuit to emit light according to the regulated driving voltage; the range of the adjusted driving voltage is larger than the voltage range of the first node.
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
An OLED (Organic Light-Emitting Diode) display device is widely used in various fields due to its advantages of self-luminescence, low power consumption, low cost, wide viewing angle, thin thickness, wide color gamut, flexibility, fast response speed, and the like. At present, brightness improvement is a bottleneck point of an OLED display technology, especially a micro OLED display technology, and the brightness improvement is mainly achieved by improving the efficiency of an OLED display device at present, but the brightness improvement range is limited, so that the brightness of the OLED display device cannot be fundamentally improved to a higher level.
In the prior art, it is proposed to increase the luminance of the light-emitting unit by increasing the voltage value of the input signal when increasing the luminance of the light-emitting unit, but in this way, the power signal input to the driving sub-circuit needs to be redesigned, and a transistor with a performance meeting the requirement needs to be selected again, resulting in a huge workload.
Disclosure of Invention
The present invention is directed to at least one of the technical problems in the prior art, and provides a pixel circuit capable of effectively improving the display brightness and contrast of a display module.
The technical scheme adopted for solving the technical problem of the invention is that the pixel circuit comprises
A driving sub-circuit configured to output a driving voltage to drive the light emitting sub-circuit to emit light in response to control of the scanning terminal;
the first end of the voltage regulation subcircuit and the output end of the driving subcircuit are connected to a first node, and the second end of the voltage regulation subcircuit and the first end of the light-emitting subcircuit are connected to a second node;
the voltage regulation subcircuit is configured to: responding to the control of a first control voltage end, carrying out voltage regulation on the voltage of the first node, and transmitting the regulated driving voltage to the second node so as to drive the light-emitting sub-circuit to emit light according to the regulated driving voltage;
the range of the adjusted driving voltage is larger than the voltage range of the first node.
Optionally, the voltage regulation sub-circuit includes: the device comprises a first energy storage unit, a control unit, a second storage unit, a second energy storage unit, a protection unit and a third storage unit; a first end of the first energy storage unit is connected with the first node, and a second end of the first energy storage unit is connected with a first end of the control unit and a first end of the second storage unit; the second end of the second storage unit is connected with the first end of the second energy storage unit and the first end of the protection unit; the second end of the protection unit and the first end of the third storage unit are connected with the second node; a second terminal of the control unit, a second terminal of the second energy storage unit, and a second terminal of the third storage unit are connected to a first reference voltage terminal; and the control end of the control unit is connected with the first control voltage end.
Further optionally, the protection unit includes a diode, and an input terminal of the diode is connected to the second terminal of the first energy storage unit; the output end is connected with the second node.
Optionally, the first energy storage unit comprises an inductive element; the first end and the first end of the inductance element are connected with the first node, and the second end of the inductance element is connected with the first end of the control unit.
Optionally, the control unit includes a control transistor, a first pole of the control transistor is connected to the second end of the first energy storage unit, a second pole of the control transistor is connected to the first reference voltage end, and a control pole of the control transistor is connected to the first control voltage end.
Optionally, the driving sub-circuit includes: the device comprises a reset unit, an input unit, a first storage unit and a drive unit; the input unit is connected with the first end of the first storage unit and the control end of the driving unit at a third node; the second end of the storage unit is connected with a second reference voltage end; the first end of the driving unit is connected with a driving voltage end; the second end of the driving unit and the first end of the resetting unit are connected to a first node; the first node is the output end of the driving sub-circuit; the first end of the reset unit is connected with a reset voltage end;
the reset unit is configured to: controlling the conduction state of a second voltage end and the third node in response to the control of the reset control end; the input unit is configured to: transmitting an input signal to a third node in response to the control of the scan terminal; the drive unit is configured to: transmitting a driving voltage to the first node in response to the control of the third node voltage.
Further optionally, the input unit includes: a first input transistor and a second input transistor, switching characteristics of the first input transistor and the second input transistor being opposite; the scanning end comprises a first scanning end and a second scanning end; the control electrode of the first input transistor is connected with the first scanning end; the control electrode of the second input transistor is connected with the second scanning end; the first poles of the first input transistor and the second input transistor are connected with a signal input end of an input signal end; second poles of the first and second input transistors are connected to the third node.
Optionally, the light emitting unit includes an OLED display device; the first pole of the OLED display device is connected with the second node; the second pole is connected to the second reference voltage terminal.
Another technical solution to solve the technical problem of the present invention is a display device including any one of the pixel circuits described above.
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 including:
providing an active level signal to a scanning end to enable the driving sub-circuit to write a driving voltage into a first node;
and providing an effective level signal to a first control voltage end so that the voltage regulation subcircuit regulates the voltage of the first node, and transmitting the regulated driving voltage to the second node so as to drive the light-emitting subcircuit to emit light according to the regulated driving voltage.
Drawings
FIG. 1 is a schematic diagram of a pixel circuit according to an embodiment of the invention;
FIG. 2 is a diagram of a driving sub-circuit in a pixel circuit according to an embodiment of the invention;
FIG. 3 is a schematic diagram of a pixel circuit according to an embodiment of the present invention;
fig. 4 is a signal timing diagram of a pixel circuit according to an embodiment of the invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
Unless otherwise defined, technical or scientific terms used in the embodiments of the present invention should have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. The use of "first," "second," and similar terms in the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. Likewise, the word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
Example 1:
the present embodiment provides a pixel circuit, as shown in fig. 1, including: a drive sub-circuit and a voltage regulation sub-circuit. Wherein the driving sub-circuit is configured to output a driving voltage to drive the light emitting sub-circuit to emit light in response to the control of the scan terminal Gate; the first end of the voltage regulation subcircuit and the output end of the driving subcircuit are connected to a first node 1, and the second end of the voltage regulation subcircuit and the first end of the light-emitting subcircuit are connected to a second node 2; the voltage regulation sub-circuit is configured to regulate a voltage of the first node 1 in response to a control of the first control voltage terminal, and transmit the regulated driving voltage to the second node 2 to drive the light emitting sub-circuit to emit light according to the regulated driving voltage. Wherein the range of the adjusted driving voltage is larger than the voltage range of the first node 1.
Compared with the prior art, in the pixel circuit provided in this embodiment, the voltage control sub-circuit is disposed between the driving sub-circuit and the light emitting sub-circuit, and the voltage control sub-circuit performs voltage regulation on the driving voltage (i.e., the voltage at the first node 1; the first driving voltage) output by the driving sub-circuit, and outputs the regulated driving voltage (the second driving voltage) to the light emitting sub-circuit to drive the light emitting sub-circuit to emit light. In this embodiment, through the voltage regulation sub-circuit, can be with first drive voltage regulation for the bigger second drive voltage of numerical range to can improve the luminance and the contrast of display module assembly, make the luminance promotion when the display module assembly can realize high grey level, luminance reduction when the low grey level not only promotes the biggest display brightness, has also improved the contrast, and then promotes the display effect of display module assembly. On the other hand, when the pixel circuit provided by the embodiment of the invention is adopted to drive the light-emitting sub-circuit (specifically the light-emitting unit) to emit light, a power supply signal input into the drive sub-circuit does not need to be redesigned, and a transistor with performance meeting requirements does not need to be reselected, so that the light-emitting brightness of the light-emitting unit at a high gray scale is improved under the condition of not increasing workload, the brightness at a low gray scale is reduced, the highest brightness is improved, and the screen contrast is improved.
Specifically, the result of the voltage regulation subcircuit on the first driving voltage may be as follows: when displaying in low gray scale, making the second driving voltage smaller than the first driving voltage; when displaying the high gray scale, the second driving voltage is larger than the first driving voltage. Therefore, when the display module comprises the pixel circuit provided by the embodiment, the light-emitting unit can realize higher light-emitting brightness and higher contrast under the driving of the pixel circuit, so that the optical effect of the display device is better improved, and the application scenes of the display device are widened.
Optionally, as shown in fig. 1 and fig. 3, in this embodiment, the voltage regulator sub-circuit may include: a first energy storage unit L1, a control unit T5, a second storage unit C2, a second energy storage unit L2, a protection unit D1, and a third storage unit C3; a first terminal of the first power storing unit L1 is connected to the first node 1, and a second terminal of the first power storing unit L1 is connected to a first terminal of the control unit T5 and a first terminal of the second storage unit C2; a second terminal of the second storage cell C2 is connected to a first terminal of the second energy storage cell L2 and a first terminal of the protection cell D1; the second terminal of the protection unit D1 and the first terminal of the third storage unit C3 are connected to the second node 2; the second terminal of the control unit T5, the second terminal of the second energy storing unit L2, and the second terminal of the third memory cell C3 are connected to a first reference voltage terminal Vcom 1; the control terminal of the control unit T5 is connected to the first control voltage terminal.
When the voltage regulation sub-circuit provided by this embodiment operates, in the charging phase, the control unit T5 is turned on under the control of the first control voltage terminal, the first energy storage unit L1 and the second energy storage unit L2 store energy, the first driving voltage output by the driving sub-circuit is transmitted to the energy storage unit, and some energy is gradually stored in the energy storage unit; at the same time, the second storage unit C2 will also transfer the energy stored in the previous stage to the second energy storage unit L2. During the energy storage process of the first energy storage unit L1 and the second energy storage unit L2, the protection unit D1 is configured to prevent the current from being reversely transmitted to the first node 1 end through the energy storage units, so as to ensure the stability of the operation of the voltage regulation sub-circuit. In the light emitting period, the control unit T5 is turned off under the control of the first control voltage terminal, the energy storage unit is disconnected from the first reference voltage terminal Vcom1, the energy storage unit has a holding characteristic for a current, and the first driving voltage and the first energy storage unit L1 both supply power to the third memory cell C3, supply a second driving voltage, and control the light emitting unit to emit light by the second driving voltage. This phase also charges the second storage cell C2, and the energy stored in the second storage cell C2 is transferred to the second energy storage cell L2 when the control cell T5 is in the on state.
The voltage (second driving voltage) finally applied to the light emitting unit is related to the on ratio of the control unit T5, and by changing the on ratio, the output voltage second driving voltage may be higher than the input voltage first driving voltage or lower than the first driving voltage, and by controlling the on ratio, the brightness and contrast of the display module may be adjusted, and since the numerical range of the second driving voltage is larger, the brightness and contrast of the display module may be improved.
Alternatively, as shown in fig. 3, in the present embodiment, the control unit T5 includes a control transistor, a first pole of the control transistor is connected to the second terminal of the first energy storage unit L1, a second pole of the control transistor is connected to the first reference voltage terminal Vcom1, and a control pole of the control transistor is connected to the first control voltage terminal. The on and off states of the control transistor can be controlled by writing an effective working level or an off level into the control electrode of the control transistor through the first control voltage end.
Optionally, the first energy storage unit L1 includes an inductive element; the first terminal and the first terminal of the inductance element are connected to the first node 1, and the second terminal is connected to the first terminal of the control unit T5.
Optionally, the protection unit D1 includes a diode, and an input terminal of the diode is connected to the second terminal of the first energy storage unit L1; the output is connected to the second node 2. In this embodiment, the unidirectional conduction performance of the diode can be utilized to prevent the reverse transmission of current to the first node 1 through the first energy storage unit L1 during the energy storage process of the energy storage unit.
Optionally, the light emitting sub-circuit comprises an OLED display device; the first pole of the OLED display device is connected with the second node 2; the second pole is connected to a second reference voltage terminal Vcom 2. Specifically, the first pole may be an anode and the second pole may be a cathode.
It should be noted that, in the pixel circuit provided in this embodiment, the first reference voltage terminal Vcom1 provides a reference voltage for one terminal of the control unit T5, the second energy storage unit L2 and the third storage unit C3 in the voltage regulation sub-circuit, and the first reference voltage terminal Vcom1 and the second reference voltage terminal Vcom2 can be the same reference voltage terminal Vcom. That is, as shown in fig. 3, as an embodiment, the second terminal of the control unit T5, the second terminal of the second energy storing unit L2, the second terminal of the third memory cell C3, and the second terminal of the light emitting cell may all be connected to the same reference voltage terminal Vcom.
Optionally, as shown in fig. 2, in the pixel circuit provided in this embodiment, the driving sub-circuit includes: a reset unit T4, an input unit, a first memory cell C1, and a driving unit T3. Wherein, the input unit and the first terminal of the first memory cell C1, the control terminal of the driving unit T3 are connected to the third node 3; the second terminal of the first memory cell C1 is connected to the second reference voltage terminal Vcom 2; the first terminal of the driving unit T3 is connected to the driving voltage terminal ELVDD; the second terminal of the driving unit T3 and the first terminal of the reset unit T4 are connected to the first node 1; the first node 1 is the output end of the driving sub-circuit; a first terminal of the reset unit T4 is connected to a reset voltage terminal; the reset unit T4 is configured to: controlling the conduction state of the second voltage terminal and the third node 3 in response to the control of the reset control terminal; the input unit is configured to: transmitting an input signal to the third node 3 in response to the control of the scan terminal Gate; the drive unit T3 is configured to: the driving voltage is transmitted to the first node 1 in response to the control of the voltage of the third node 3.
Optionally, the reset unit T4 includes a reset transistor, a control electrode of the reset transistor is connected to the reset control terminal, a first electrode of the reset transistor is connected to the first node 1, and a second electrode of the reset transistor is connected to the reset voltage terminal. Alternatively, the reset voltage terminal may be the ground terminal GND.
The display module generally includes a plurality of display cycles when realizing the display function, and in each display cycle, the pixel circuit includes four periods, as shown in fig. 4, specifically includes: the reset period P1, the data write period P2, the voltage adjustment charging period P3, and the light emission period P4, the following is a driving process of the pixel circuit provided for the present embodiment in conjunction with fig. 3 and 4.
In the reset period P1, an active working level is written into the reset control terminal, the reset unit T4 is controlled to be turned on, and the driving sub-circuit is turned on with the reset voltage terminal, so that the first energy storage unit can be discharged sequentially through the driving unit T3 and the reset unit T4, thereby implementing initialization of the first energy storage unit.
In the data write period P2, an off level is written to the reset control section, controlling the reset unit T4 to turn off. And writing an effective working level into the scanning end Gate, and controlling the input unit to be conducted, so that an input signal written by the signal input end Data is written into a control end (namely, the third node 3) of the driving unit T3, and charging of the first energy storage unit C1 is realized.
In the voltage regulation charging period P3, an active operation level is written to the first control voltage terminal, the control unit T5T5 is turned on, the first energy storage unit L1L1 is connected to the first reference voltage terminal Vcom1, the first memory cell C1C1 is discharged, so that the driving unit T3 is in an operation state, a loop formed by the first driving voltage-the first energy storage unit L1-the control unit T5-the first reference voltage short and a loop formed by the second memory cell C2-the control unit T5-the second energy storage unit L2 are simultaneously conductive, and the first energy storage unit L1 and the second energy storage unit L2 are simultaneously conductive. The first driving voltage output by the driving sub-circuit is transmitted from the first node 1 to the first energy storage unit L1, and since the direct current is input to the first energy storage unit L1, the inductance element of the first energy storage unit L1 blocks the change of the current, so that the current on the inductance element linearly increases at a certain rate, and as the current on the inductance element increases, some energy is gradually stored in the first energy storage unit L1; meanwhile, the second storage unit C2 will transfer the energy stored in the previous stage to the second energy storage unit L2, so that the first energy storage unit L1 and the second energy storage unit L2 store energy in this stage.
In the light emission period P4, the control unit T5 is turned off, the first energy storage unit L1 is disconnected from the first reference voltage terminal Vcom1, and since the inductance unit has a holding characteristic for a current, a loop made up of the first driving voltage-the first energy storage unit L1-the second storage unit C2-the protection unit D1-the load (the third storage capacitor and the light emitting unit) and a loop made up of the second energy storage unit L2-the protection unit D1-the load are simultaneously conductive. Since the inductance element has a holding characteristic for a current, the first driving voltage and the first energy storage unit L1 both supply power to the load at this stage, supply the second driving voltage, and control the light emitting unit to emit light by the second driving voltage. This phase also charges the second storage capacitor, and the energy stored in the second storage capacitor is transferred to the second energy storage unit L2 when the control unit T5 is in the on state.
It should be noted that, in the light emitting period P4, the voltage V of the second node 2 (the second driving voltage; i.e. the voltage finally applied to the light emitting cell)out＝Vin*ton/toff＝Vin*ton/(T-ton)＝Vinα/(1- α), wherein α ═ ton/T,T＝(ton+toff). Wherein, VinIs the input voltage of the light-emitting sub-circuitI.e. the voltage of the first node 1 (the first driving voltage output by the driving sub-circuit); t is tonIs the on-time of control unit T5 during one cycle; t is toffIs the off time of control unit T5 in one cycle. It can be seen that the second driving voltage is related to not only the first and second changed on ratios but also the on ratio of the control unit T5. When the first driving voltage is constant, the magnitude of the output second driving voltage can be adjusted by controlling the on-ratio of the control means T5, and the second driving voltage output by the voltage adjustment sub-circuit may be higher than the input voltage and the first driving voltage or may be lower than the first driving voltage. Specifically, when 0<α<1/2 the voltage regulator sub-circuit can realize voltage reduction when 1/2<α<The 1-time voltage regulation sub-circuit can realize boosting. Therefore, the pixel circuit provided by the embodiment can adjust the turn-on ratio of the control unit T5 to make 0 in low gray scale display<α<1/2, the second driving voltage is less than the first driving voltage, so that the display brightness of the display module can be lower; at high gray level, 1/2<α<And 1, the second driving voltage is greater than the first driving voltage, so that the display brightness and the contrast of the display module are improved.
Optionally, in the pixel circuit provided in this embodiment, the input unit may include: the switching characteristics in the first input transistor T1 and the second input transistor T2, the first input transistor T1 and the second input transistor T2 are opposite; the scan terminal Gate includes a first scan terminal Gate1 and a second scan terminal Gate 2; a control electrode of the first input transistor T1 is connected to the first scan terminal Gate 1; a control electrode of the second input transistor T2 is connected to the second scan terminal Gate 2; first poles of the first input transistor T1 and the second input transistor T2 are connected to the signal input terminal Data; the second poles of the first and second input transistors T1 and T2 are connected to the third node 3.
In the pixel circuit provided by this embodiment, the scan terminal Gate may include a first scan terminal Gate11 and a second scan terminal Gate 2; so that the first input transistor T1 and the second input transistor T2 can better write the input signal to the gate of the driving transistor in the data write period P2. In addition, in other periods except for the Data writing period P2, the first input transistor T1 and the second input transistor T2 jointly control to disconnect the connection between the Gate terminal Data of the scanning terminal and the Gate terminal of the driving transistor DTFT, so that the driving transistor DTFT and the signal input terminal Data can be disconnected more thoroughly, thereby better ensuring the stability of the operation of the pixel circuit.
Wherein the switching characteristics of the first input transistor T1 model and the second input transistor T2 are opposite. Illustratively, the first input transistor T1 is an N-type transistor and the second input transistor T2 is a P-type transistor. In addition, the driving transistor T3, the reset transistor T4, and the control transistor T5 may be N-type transistors or P-type transistors. The description is given for the sake of example.
Example 2:
the embodiment also provides a display device, and the pixel circuit provided in embodiment 1.
The display device may be: the display device comprises any product or component with a display function, such as electronic paper, an OLED panel, a mobile phone, a tablet computer, a television, a display, a notebook computer, a digital photo frame, a navigator and the like.
The display device adopts the pixel circuit, can improve the brightness and the contrast of the display module, enables the display module to achieve brightness improvement when in high gray scale, reduces the brightness when in low gray scale, improves the maximum display brightness, also improves the contrast, and further improves the display effect of the display module. On the other hand, the display device does not need to redesign a power supply signal input into the driving sub-circuit and reselect a transistor with performance meeting requirements, so that the brightness of the light-emitting unit is improved when the gray scale is high and the brightness of the light-emitting unit is reduced when the gray scale is low under the condition of not increasing workload, the highest brightness is improved, and the screen contrast is improved.
Example 3:
the present embodiment provides a driving method applied to any one of the pixel circuits in embodiment 1, the driving method including:
providing an effective level signal to the scan terminal Gate to make the driving sub-circuit write the driving voltage into the first node 1;
and providing an effective level signal to the first control voltage end so that the voltage regulation subcircuit regulates the voltage of the first node 1, and transmitting the regulated driving voltage to the second node 2 so as to drive the light-emitting subcircuit to emit light according to the regulated driving voltage.
Specifically, in one display cycle, each of the pixel circuits includes four periods, as shown in fig. 4, specifically including: the reset period P1, the data write period P2, the voltage adjustment charging period P3, and the light emission period P4 are described below with reference to fig. 3 and 4 as a driving method of the pixel circuit provided in the present embodiment.
In the reset period P1, an active working level is written into the reset control terminal, the reset unit T4 is controlled to be turned on, and the driving sub-circuit is turned on with the reset voltage terminal, so that the first energy storage unit can be discharged sequentially through the driving unit T3 and the reset unit T4, thereby implementing initialization of the first energy storage unit.
In the data write period P2, an off level is written to the reset control section, controlling the reset unit T4 to turn off. And writing an effective working level into the scanning end Gate, and controlling the input unit to be conducted, so that an input signal written by the signal input end Data is written into a control end (namely, the third node 3) of the driving unit T3, and charging of the first energy storage unit C1 is realized.
In the voltage regulation charging period P3, an active operation level is written to the first control voltage terminal, the control unit T5T5 is turned on, the first energy storage unit L1L1 is connected to the first reference voltage terminal Vcom1, the first memory cell C1C1 is discharged, so that the driving unit T3 is in an operation state, a loop formed by the first driving voltage-the first energy storage unit L1-the control unit T5-the first reference voltage short and a loop formed by the second memory cell C2-the control unit T5-the second energy storage unit L2 are simultaneously conductive, and the first energy storage unit L1 and the second energy storage unit L2 are simultaneously conductive. The first driving voltage output by the driving sub-circuit is transmitted from the first node 1 to the first energy storage unit L1, and since the direct current is input to the first energy storage unit L1, the inductance element of the first energy storage unit L1 blocks the change of the current, so that the current on the inductance element linearly increases at a certain rate, and as the current on the inductance element increases, some energy is gradually stored in the first energy storage unit L1; meanwhile, the second storage unit C2 will transfer the energy stored in the previous stage to the second energy storage unit L2, so that the first energy storage unit L1 and the second energy storage unit L2 store energy in this stage.
In the light emission period P4, the control unit T5 is turned off, the first energy storage unit L1 is disconnected from the first reference voltage terminal Vcom1, and since the inductance unit has a holding characteristic for a current, a loop made up of the first driving voltage-the first energy storage unit L1-the second storage unit C2-the protection unit D1-the load (the third storage capacitor and the light emitting unit) and a loop made up of the second energy storage unit L2-the protection unit D1-the load are simultaneously conductive. By using the holding characteristic of the inductance element to the current, the first driving voltage and the first energy storage unit L1 both supply power to the load at this stage, provide the second driving voltage, and control the light emitting unit to emit light by the second driving voltage. This phase also charges the second storage capacitor, and the energy stored in the second storage capacitor is transferred to the second energy storage unit L2 when the control unit T5 is in the on state.
It is to be noted herein that, in the light emitting period P4, the voltage Vout of the second node 2 is related to not only the first-second changing on ratio but also the on ratio of the control unit T5. When the first driving voltage is constant, the magnitude of the output second driving voltage can be adjusted by controlling the on-ratio of the control means T5, and the second driving voltage output by the voltage adjustment sub-circuit may be higher than the input voltage and the first driving voltage or may be lower than the first driving voltage. Specifically, the voltage regulating sub-circuit can implement the step-down when 0< the on ratio of the control unit T5 <1/2, and the voltage regulating sub-circuit can implement the step-up when 1/2< the on ratio of the control unit T5 < 1. Therefore, in the pixel circuit provided by the embodiment, the on ratio of the control unit T5 can be adjusted, so that the second driving voltage is smaller than the first driving voltage during low gray scale display, and the display brightness of the display module can be lower; and when the gray scale is high, the second driving voltage is greater than the first driving voltage, so that the display brightness and the contrast of the display module are improved.
It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.
Claims (9)
1. A pixel circuit, comprising:
a driving sub-circuit configured to output a driving voltage to drive the light emitting sub-circuit to emit light in response to control of the scanning terminal;
the first end of the voltage regulation subcircuit and the output end of the driving subcircuit are connected to a first node, and the second end of the voltage regulation subcircuit and the first end of the light-emitting subcircuit are connected to a second node;
the voltage regulation subcircuit is configured to: responding to the control of a first control voltage end, carrying out voltage regulation on the voltage of the first node, and transmitting the regulated driving voltage to the second node so as to drive the light-emitting sub-circuit to emit light according to the regulated driving voltage;
the range of the adjusted driving voltage is larger than the voltage range of the first node;
the voltage regulation subcircuit includes: the device comprises a first energy storage unit, a control unit, a second storage unit, a second energy storage unit, a protection unit and a third storage unit; a first end of the first energy storage unit is connected with the first node, and a second end of the first energy storage unit is connected with a first end of the control unit and a first end of the second storage unit; the second end of the second storage unit is connected with the first end of the second energy storage unit and the first end of the protection unit; the second end of the protection unit and the first end of the third storage unit are connected with the second node; a second terminal of the control unit, a second terminal of the second energy storage unit, and a second terminal of the third storage unit are connected to a first reference voltage terminal; the control end of the control unit is connected with the first control voltage end;
the first energy storage unit comprises an inductance element, a first end of the inductance element is connected with the first node, and a second end of the inductance element is connected with a first end of the control unit and a first end of the second storage unit;
the second storage unit comprises a capacitor element, and the second end of the capacitor element is connected with the first end of the second energy storage unit and the first end of the protection unit;
the second energy storage unit comprises an inductance element, and a second end of the inductance element and a second end of the third storage unit are connected with a first reference voltage end;
the third storage unit includes a capacitance element having a first terminal connected to the second node.
2. The pixel circuit according to claim 1, wherein the protection unit includes a diode, an input terminal of the diode being connected to the second terminal of the first energy storage unit; the output end is connected with the second node.
3. The pixel circuit according to claim 1, wherein the first energy storage unit comprises an inductive element; the first end and the first end of the inductance element are connected with the first node, and the second end of the inductance element is connected with the first end of the control unit.
4. The pixel circuit according to claim 1, wherein the control unit comprises a control transistor having a first pole coupled to the second terminal of the first energy storage unit, a second pole coupled to the first reference voltage terminal, and a control pole coupled to the first control voltage terminal.
5. The pixel circuit of claim 1, wherein the drive sub-circuit comprises: the device comprises a reset unit, an input unit, a first storage unit and a drive unit; the input unit is connected with the first end of the first storage unit and the control end of the driving unit at a third node; the second end of the storage unit is connected with a second reference voltage end; the first end of the driving unit is connected with a driving voltage end; the second end of the driving unit and the first end of the resetting unit are connected to a first node; the first node is the output end of the driving sub-circuit; the first end of the reset unit is connected with a reset voltage end;
the reset unit is configured to: controlling the conduction state of a second voltage end and the third node in response to the control of a reset control end; the input unit is configured to: transmitting an input signal to a third node in response to the control of the scan terminal; the drive unit is configured to: transmitting a driving voltage to the first node in response to the control of the third node voltage.
6. The pixel circuit according to claim 5, wherein the input unit comprises: a first input transistor and a second input transistor, switching characteristics of the first input transistor and the second input transistor being opposite; the scanning end comprises a first scanning end and a second scanning end; the control electrode of the first input transistor is connected with the first scanning end; the control electrode of the second input transistor is connected with the second scanning end; first poles of the first input transistor and the second input transistor are connected with a signal input end; second poles of the first and second input transistors are connected to the third node.
7. The pixel circuit of claim 1, wherein the light emitting sub-circuit comprises an OLED display device; the first pole of the OLED display device is connected with the second node; the second pole is connected to the second reference voltage terminal.
8. A display device comprising the pixel circuit according to any one of claims 1 to 7.
9. A driving method applied to the pixel circuit according to any one of claims 1 to 7, wherein the driving method comprises:
providing an active level signal to a scanning end to enable the driving sub-circuit to write a driving voltage into a first node;
and providing an effective level signal to a first control voltage end so that the voltage regulation subcircuit regulates the voltage of the first node, and transmitting the regulated driving voltage to the second node so as to drive the light-emitting subcircuit to emit light according to the regulated driving voltage.
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