CN114255691A - Pixel circuit, driving method thereof and display device - Google Patents
Pixel circuit, driving method thereof and display device Download PDFInfo
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- CN114255691A CN114255691A CN202011014626.XA CN202011014626A CN114255691A CN 114255691 A CN114255691 A CN 114255691A CN 202011014626 A CN202011014626 A CN 202011014626A CN 114255691 A CN114255691 A CN 114255691A
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- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- 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]
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Abstract
The application discloses a pixel circuit, a driving method thereof and a display device. The pixel circuit provided by the application comprises a drive control unit, an input control unit and an isolation unit, wherein: a driving control unit including a light emitting device for supplying a driving current to the light emitting device; the isolation unit is used for isolating the light-emitting time control signal input by the input control unit from the drive control unit; and the input control unit is used for outputting the input light-emitting time control signal to the isolation unit and transmitting the input light-emitting time control signal to the drive control unit through the isolation unit so as to control the light-emitting time of the light-emitting device. According to the embodiment of the application, the isolation unit is arranged, the isolated input light-emitting time control signal is isolated from the drive control unit, the grid voltage change of the drive transistor on a current path in the drive control unit caused by the signal writing is avoided, the light-emitting device is guaranteed to normally emit light at the design moment, and the wide application prospect is achieved.
Description
Technical Field
The present disclosure relates to the field of display technologies, and in particular, to a pixel circuit, a driving method thereof, and a display device.
Background
The micro LED is a new generation display technology, has higher brightness, better luminous efficiency and lower power consumption than the existing OLED technology, and therefore, the excellent characteristics of the micro LED enable the micro LED to be applied to televisions, iPhones and iPads. Meanwhile, the micro led is a self-light emitting device, and its light emitting efficiency is reduced with the decrease of current density at low current density. In contrast, different gray scales of OLED display are realized by driving OLED devices with different current densities to emit light with different brightness. However, in the micro led display, only the current density is changed to realize the brightness of different gray scales, and thus, the light emitting efficiency is low and the power consumption is high due to the low current density in the low gray scale.
In order to enable the mircoLED to work at high current density, as shown in fig. 1, which is a schematic diagram of a pixel driving circuit of a micro LED in the prior art, a PWM control module is introduced to a current path to control the conducting time of the current path. When the Vdata _ T of the PWM is written, due to the capacitive coupling effect, the gate voltage of a DTFT (Drive Thin Film Transistor) T4 in the Vdata _ T is changed, before the gate b is turned on, the gate of the T8 is in a floating state, after the gate b is turned on, the Vdata _ T is written, the gate voltage of the T8 is changed, due to the coupling effect of the T8 Cgs, the drain voltage of the T4 is changed, and under the coupling effect of the Cgd, the gate voltage of the T4 is changed, so that the light emitting element cannot be normally turned on.
Disclosure of Invention
In order to solve at least one of the above problems, a first aspect of the present application provides a pixel circuit including a drive control unit, an input control unit, and an isolation unit, wherein:
a driving control unit including a light emitting device for supplying a driving current to the light emitting device; the isolation unit is used for isolating the light-emitting time control signal input by the input control unit from the drive control unit; and the input control unit is used for outputting the input light-emitting time control signal to the isolation unit and transmitting the input light-emitting time control signal to the drive control unit through the isolation unit so as to control the light-emitting time of the light-emitting device.
In some optional embodiments, the isolation unit comprises a first isolation transistor, a second isolation transistor and a first isolation capacitor, wherein
A first electrode of the first isolation transistor is connected to a light-emitting time control signal output by the input control unit, a second electrode of the first isolation transistor is connected to a first node, a control electrode of the first isolation transistor is connected to the first light-emitting control signal, and the first node is a connection node of the isolation unit and the drive control unit;
a first pole of the second isolation transistor is connected to a first power supply signal, a second pole of the second isolation transistor is connected to a first node, and a control pole of the second isolation transistor is connected to a reset signal;
the first end of the first isolation capacitor is connected to the first node, and the second end of the first isolation capacitor is connected to the second power supply signal.
In some alternative embodiments, the driving control unit includes a light emitting unit including a light emitting switching transistor and a light emitting device; a pixel driving unit for supplying a driving current to the light emitting device through the light emitting switching transistor; a first electrode of the light-emitting switch transistor is connected to a driving current signal output by the pixel driving unit, a second electrode of the light-emitting switch transistor is connected to a first electrode of the light-emitting device, and a control electrode of the light-emitting switch transistor is connected to a first node; the second pole of the light emitting device is connected to a third power supply signal.
In some alternative embodiments, the pixel driving unit includes: scanning switch transistor, drive transistor, threshold compensation transistor, first reset transistor, first lighting control transistor and drive storage capacitor, wherein:
a first electrode of the scanning switch transistor is connected with a data voltage signal, a second electrode of the scanning switch transistor is connected to a second node, and a control electrode of the scanning switch transistor is connected with a row scanning signal of the pixel circuit;
the first pole of the driving transistor is connected to the second node, the second pole is connected to the first pole of the luminous switch transistor, and the control pole is connected to the third node;
the first pole of the threshold compensation transistor is connected to the third node, the second pole of the threshold compensation transistor is connected to the second pole of the driving transistor, and the control pole of the threshold compensation transistor is connected to a row scanning signal of the pixel circuit;
a first pole of the first reset transistor is connected to the third node, a second pole of the first reset transistor is connected to the fourth power supply signal, and a control pole of the first reset transistor is connected to the reset signal;
a first pole of the first light-emitting control transistor is connected to a fifth power supply signal, a second pole of the first light-emitting control transistor is connected to the second node, and a control pole of the first light-emitting control transistor is connected to the first light-emitting control signal;
the first end of the driving storage capacitor is connected to the fourth node, and the second end of the driving storage capacitor is connected to the third node.
In some alternative embodiments, the input control unit comprises an input transistor and an input storage capacitor, wherein:
the first pole of the input transistor is connected with a light-emitting time control signal, the second pole of the input transistor is connected with the first pole of the first isolation transistor of the isolation unit, and the control pole of the input transistor is connected with a second light-emitting control signal; the first end of the input storage capacitor is connected to the first pole of the first isolation transistor of the isolation unit, and the second end of the input storage capacitor is connected to the second power supply signal.
A second aspect of the present application provides a display device comprising the pixel circuit according to the first aspect of the present application.
A third aspect of the present application provides a driving method of the pixel circuit according to the first aspect of the present application, including: the isolation unit isolates the light-emitting time control signal input by the input control unit from the drive control unit, and the drive control unit comprises a light-emitting device; the driving control unit supplies a driving current to the light emitting device; the input control unit outputs the input light-emitting time control signal to the isolation unit and transmits the input light-emitting time control signal to the drive control unit through the isolation unit so as to control the light-emitting time of the light-emitting device.
In some optional embodiments, the isolation unit includes a first isolation transistor, a second isolation transistor, and a first isolation capacitor, where a first pole of the first isolation transistor is connected to the light-emitting time control signal output by the input control unit, a second pole of the first isolation transistor is connected to a first node, a control pole of the first isolation transistor is connected to the first light-emitting control signal, and the first node is a connection node between the isolation unit and the drive control unit; a first pole of the second isolation transistor is connected to a first power supply signal, a second pole of the second isolation transistor is connected to a first node, and a control pole of the second isolation transistor is connected to a reset signal; the first end of the first isolation capacitor is connected to the first node, and the second end of the first isolation capacitor is connected to the second power supply signal;
the driving method comprises the following steps:
a reset stage: the second isolation transistor outputs a first power supply signal to the drive control unit in response to a reset signal;
data write and threshold compensation phases: the driving control unit supplies a driving current to the light emitting device;
and a light emitting control stage: the method comprises the following steps:
time control signal writing stage: the input control unit outputs the input light-emitting time control signal to the isolation unit;
a light emitting stage: the first isolation transistor transmits a light emission time control signal to the driving control unit in response to the first light emission control signal to control the light emitting device to emit light.
In some of the alternative embodiments, the first and second,
the driving control unit comprises a light emitting unit and a pixel driving unit, the light emitting unit comprises a light emitting switch transistor and a light emitting device, wherein a first pole of the light emitting switch transistor is connected to a driving current signal output by the pixel driving unit, a second pole of the light emitting switch transistor is connected to a first pole of the light emitting device, and a control pole of the light emitting switch transistor is connected to a first node; the second pole of the light-emitting device is connected with a third power supply signal;
the pixel driving unit includes: the pixel circuit comprises a scanning switch transistor, a driving transistor, a threshold compensation transistor, a first reset transistor, a first light-emitting control transistor and a driving storage capacitor, wherein a first pole of the scanning switch transistor is connected with a data voltage signal, a second pole of the scanning switch transistor is connected to a second node, and a control pole of the scanning switch transistor is connected with a row scanning signal of the pixel circuit; the first pole of the driving transistor is connected to the second node, the second pole is connected to the first pole of the luminous switch transistor, and the control pole is connected to the third node; the first pole of the threshold compensation transistor is connected to the third node, the second pole is connected to the second pole of the driving transistor, and the control pole is connected to the row scanning signal of the pixel circuit; a first pole of the first reset transistor is connected to the third node, a second pole of the first reset transistor is connected to the fourth power supply signal, and a control pole of the first reset transistor is connected to the reset signal; a first pole of the first light-emitting control transistor is connected to a fifth power supply signal, a second pole of the first light-emitting control transistor is connected to the second node, and a control pole of the first light-emitting control transistor is connected to the first light-emitting control signal; a first end of the driving storage capacitor is connected to a fifth power supply signal, and a second end of the driving storage capacitor is connected to a third node;
the reset phase further comprises: the second isolation transistor responds to a reset signal to output a first power supply signal to a control electrode of the light-emitting switch transistor, the first reset transistor responds to a reset signal RST to discharge the driving storage capacitor, and outputs a fourth power supply signal to a control electrode of the driving transistor to turn on the driving transistor;
the data write and threshold compensation phase further comprises: the scan switching transistor transmits an input data voltage signal to a first pole of the driving transistor in response to a row scan signal of the pixel circuit; the threshold compensation transistor compensates a threshold voltage of the driving transistor in response to a row scan signal of the pixel circuit; the driving transistor is switched on, the data voltage signal is transmitted to the grid electrode of the driving transistor through the threshold compensation transistor, and the storage capacitor is driven to store the data voltage signal; the first light-emitting control transistor provides a fifth power supply signal to the driving transistor in response to the first light-emitting control signal to form a current path, and the driving transistor generates a driving current signal and transmits the driving current signal to the first pole of the light-emitting switch transistor;
the timing control signal writing stage further includes: the input control unit outputs the input light-emitting time control signal to a first pole of a first isolation transistor of the isolation unit;
the lighting phase further comprises: the first isolation transistor transmits a light emitting time control signal to a control electrode of a light emitting switching transistor of the driving control unit in response to the first light emitting control signal, so that the driving current signal is applied to a first electrode of the light emitting device and drives the light emitting device to emit light.
In some alternative embodiments, the input control unit comprises an input transistor and an input storage capacitor, wherein: the first pole of the input transistor is connected with a light-emitting time control signal, the second pole of the input transistor is connected with the first pole of the first isolation transistor of the isolation unit, and the control pole of the input transistor is connected with a second light-emitting control signal; the first end of the input storage capacitor is connected to the first pole of the first isolation transistor of the isolation unit, and the second end of the input storage capacitor is connected to a second power supply signal;
the timing control signal writing stage further includes: the input transistor stores a light emission time control signal in the input storage capacitor in response to the second light emission control signal to transmit the light emission time control signal to a first pole of a first isolation transistor of the isolation unit.
In some optional embodiments, the first lighting control signal comprises at least two active inputs, the lighting control phase further comprising:
and transmitting a light emitting time control signal to a control electrode of a light emitting switch transistor of the driving control unit according to the first light emitting control signal so that the driving current signal is loaded to the first electrode of the light emitting device and drives the light emitting device to emit light, wherein the time control signal is the light emitting time control signal input by the input control unit in a time control signal writing stage.
The invention has the following beneficial effects:
the pixel circuit, the driving method thereof and the display device are made to solve the existing problems at present, the isolation unit is arranged between the driving control unit and the input control unit, the input light-emitting time control signal is isolated from the driving control unit, the grid voltage change of the driving transistor on a current path in the driving control unit caused by the writing of the light-emitting time control signal is avoided, the false starting of the driving transistor is further avoided, the light-emitting device is ensured to normally emit light at the design moment, the display panel can accurately display according to the modulated gray scale, and the display device has wide application prospect.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic circuit schematic diagram of a prior art pixel circuit.
Fig. 2 is a schematic circuit schematic diagram of a pixel circuit according to an embodiment of the present application.
FIG. 3 is a timing diagram of key signals in a pixel circuit according to an embodiment of the present application.
Detailed Description
In order to more clearly illustrate the present application, the present application is further described below in conjunction with the preferred embodiments and the accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not intended to limit the scope of the present application.
It is noted that references herein to "on … …", "formed on … …" and "disposed on … …" can mean that one layer is formed or disposed directly on another layer or that one layer is formed or disposed indirectly on another layer, i.e., there is another layer between the two layers. As used herein, unless otherwise specified, the term "on the same layer" means that two layers, components, members, elements or portions can be formed by the same patterning process, and the two layers, components, members, elements or portions are generally formed of the same material. Herein, unless otherwise specified, the expression "patterning process" generally includes the steps of coating of photoresist, exposure, development, etching, stripping of photoresist, and the like. The expression "one-time patterning process" means a process of forming a patterned layer, member, or the like using one mask plate.
It should be further noted that, in the embodiments of the present application, the transistors are all P-type transistors, but those skilled in the art can understand that the transistors in the present application can all be N-type transistors, and when the transistors are N-type transistors, only the level of the signal applied to the control electrode of the transistor needs to be adjusted appropriately.
As shown in fig. 2, an embodiment of the present application provides a pixel circuit, which is characterized by comprising a driving control unit, an input control unit, and an isolation unit, wherein:
a driving control unit including a light emitting device for supplying a driving current to the light emitting device;
the isolation unit is used for isolating the light-emitting time control signal input by the input control unit from the drive control unit;
and the input control unit is used for outputting the input light-emitting time control signal to the isolation unit and transmitting the input light-emitting time control signal to the drive control unit through the isolation unit so as to control the light-emitting time of the light-emitting device.
In this embodiment, by arranging the isolation unit between the driving control unit and the input control unit, the input light-emitting time control signal is isolated from the driving control unit, so that the gate voltage change of the driving transistor on a current path in the driving control unit is avoided when the light-emitting time control signal is written in, and the false turn-on of the driving transistor is further avoided, thereby ensuring that the light-emitting device normally emits light at the design moment, enabling the display panel to accurately display according to the modulated gray scale, and having wide application prospect.
In a specific example, as shown in fig. 2, the pixel circuit includes a drive control unit 101, an input control unit 103, and an isolation unit 105. Wherein the driving control unit includes a light emitting device D for supplying a driving current to the light emitting device D. The light emitting device may be a micro led, but the present application is not limited thereto, and may be other light emitting devices whose display brightness is affected by time. The isolation unit 105 is disposed between the input control unit 103 and the driving control unit, and is configured to isolate the light-emitting time control signal Vdata _ T input by the input control unit 103 from the driving control unit 101, and the input control unit 103 is configured to output the input light-emitting time control signal Vdata _ T to the isolation unit and transmit the input light-emitting time control signal Vdata _ T to the driving control unit 101 through the isolation unit to control the light-emitting time of the light-emitting device D.
Specifically, the isolation unit 105 may include a first isolation transistor T9, a second isolation transistor T10, and a first isolation capacitor C3, wherein a first pole of the first isolation transistor T9 is connected to the light emission time control signal output by the input control unit 103, a second pole is connected to a first node N1, a control pole is connected to the first light emission control signal EM, the first node N1 is a connection node of the isolation unit 105 and the driving control unit 101, and the first isolation transistor T9 transmits the light emission time control signal Vdata _ T input by the first input control unit to the driving control unit in response to the first light emission control signal EM; the first pole of the second isolation transistor T10 is connected to the first power signal VGH, the second pole is connected to the first node N1, the control pole is connected to the reset signal RST, and the second isolation transistor T10 resets the control pole of the light emitting transistor T8 in the driving control unit 101 in response to the reset signal RST, i.e., the control pole of the light emitting transistor T8 is pulled high by the first power signal VGH; the first end of the first isolation capacitor C3 is connected to the first node N1, the second end is connected to the second power signal Vcom, and the first isolation capacitor C3 is used for storing and maintaining the potential of the gate of the light emitting transistor T8, i.e., maintaining the first power signal VGH which pulls the control electrode of the light emitting transistor T8 high.
Specifically, the drive control unit 101 includes a light emitting unit 101-1 and a pixel driving unit 101-2, wherein the light emitting unit 101-1 includes a light emitting switching transistor T8 and a light emitting device D. Alternatively, the light emitting device D may be a micro led, but the present application is not limited thereto, and other semiconductor light emitting devices whose light emission degree is affected by time are also possible. The pixel driving unit 101-2 serves to supply a driving current to the light emitting device D through the light emitting switching transistor T8. The light emitting switching transistor T8 has a first electrode connected to the driving current signal output from the pixel driving unit 101-2, a second electrode connected to the first electrode of the light emitting device D, and a control electrode connected to the first node N1 to receive the light emitting time control signal Vdata _ T transmitted from the isolation unit 105. The second pole of the light emitting device D is connected to the third power signal VGND. The light emitting switching transistor T8 is turned on in response to Vdata _ T transmitted from the isolation unit 105, and applies a driving current signal to the first pole of the light emitting device D to control the light emitting device D to emit light.
The pixel driving unit 101-2 includes a scan switch transistor T2, a driving transistor T4, a threshold compensation transistor T3, a first reset transistor T1, a first light emission control transistor T5, and a driving storage capacitor C1, wherein a first pole of the scan switch transistor T2 is connected to a data voltage signal Vdata _ I, a second pole is connected to a second node N2, a control pole is connected to a row scan signal GateA of the pixel circuit, and the scan switch transistor T2 transmits the data voltage signal Vdata _ I (where N is a positive integer and a maximum value is a total number of rows of pixels to be scanned) in response to an input nth row scan signal GateA. The driving transistor T4 has a first electrode connected to the second node N2, a second electrode connected to the first electrode of the light emitting switching transistor T8, and a control electrode connected to the third node N3, and the driving transistor T4 generates a driving current signal according to the data voltage signal Vdata _ I transmitted from the scan switching transistor T2. The threshold compensation transistor T3 has a first electrode connected to the third node N3, a second electrode connected to the second electrode of the driving transistor T4, and a control electrode connected to the row scan signal GateA of the pixel circuit. The threshold compensation transistor T3 compensates the threshold voltage of the driving transistor T4 in response to the nth row scan signal GataA. Specifically, when the scan transistor T2 is turned on in response to the nth row scan signal GataA, the data voltage signal Vdata _ I is transmitted to the control electrode of the drive transistor T4 because the drive transistor T4 is turned on and the threshold compensation transistor T3 is turned on. The first reset transistor T1 has a first electrode connected to the third node N3, a second electrode connected to the fourth power signal Vinit, and a control electrode connected to the reset signal RST, and the first reset transistor T1 discharges the driving storage capacitor C1 by the fourth power signal Vinit in response to the reset signal RST, and transmits the fourth power signal Vinit to the control electrode of the driving transistor T4 to turn on the driving transistor T4. The first emission control transistor T5 has a first pole connected to the fifth power signal Vdd, a second pole connected to the second node N2, and a control pole connected to the first emission control signal EM, and the first emission control transistor T5 supplies the fifth power signal Vdd to the driving transistor T4 in response to the first emission control signal EM to form a current path to transmit the driving current signal to the first pole of the emission switching transistor T8. The first terminal of the driving storage capacitor C1 is connected to a fourth node N4, which is a node between the connection terminal of the fifth power signal Vdd and the first terminal of the first light emission control transistor T5, and the second terminal thereof is connected to the third node N3, and the driving storage capacitor C1 is used to store the data voltage signal transmitted to the control electrode of the switching transistor T2.
In addition, the input control unit 103 specifically includes an input transistor T7 and an input storage capacitor C2. The input transistor T7 has a first electrode connected to the emission time control signal Vdata _ T, a second electrode connected to the first electrode of the first isolation transistor T9 of the isolation unit 105, and a control electrode connected to the second emission control signal GateB, and the input transistor T7 transmits the emission time control signal Vdata _ T to the isolation unit 105 in response to the second emission control signal GateB. The first terminal of the input storage capacitor C2 is connected to the first pole of the first isolation transistor T9 of the isolation unit, the second terminal is connected to the second power signal Vcom, and the input storage capacitor C2 is used for storing the light emitting time control signal Vdata _ T.
With the pixel circuit according to the embodiment of the present application, the light emission time control signal Vdata _ T input by the input control unit 103 can be isolated from the driving control unit by providing the isolation unit 105 between the input control unit 103 and the driving control unit 101, so that the gate voltage variation of the driving transistor on the current path in the driving control unit 101 when the light emission time control signal Vdata _ T is written is avoided.
In order to clarify the operation principle of the pixel circuit in the embodiment of the present application, the following describes a driving method of the pixel circuit in the embodiment of the present application, and a specific process is described with reference to the timing chart in fig. 3 in combination with fig. 2.
An embodiment of the present application provides a driving method using the pixel circuit of the first aspect of the present application, including:
the isolation unit isolates the light-emitting time control signal input by the input control unit from the drive control unit, and the drive control unit comprises a light-emitting device;
the driving control unit supplies a driving current to the light emitting device;
the input control unit outputs the input light-emitting time control signal to the isolation unit and transmits the input light-emitting time control signal to the drive control unit through the isolation unit so as to control the light-emitting time of the light-emitting device.
Specifically, referring to fig. 3, a driving method of a pixel circuit according to an embodiment of the present application is described by taking as an example that the pixel circuit includes the driving control unit 101, the input control unit 103, and the isolation unit 105 shown in fig. 2, and the driving method includes:
a reset stage: the second isolation transistor T10 outputs the first power supply signal VGH to the drive control unit 101 in response to the reset signal RST, wherein, in particular, when the reset signal RST is at a low level, the second isolation transistor T10 is turned on in response to the reset signal RST received at the control electrode, thereby outputting the first power supply signal VGH to the control electrode of the light emitting switch transistor T8. It will be understood by those skilled in the art that for the P-type transistor in the example of the present application, the first power signal VGH is high level, the light emitting switching transistor T8 is turned off, the light emitting device D does not get any driving current, and the first power signal VGH charges the first isolation capacitor C3. In addition, in the reset phase, in response to the reset signal RST, the first reset transistor T1 is turned on, discharging the driving storage capacitor C1 and outputting the fourth power signal Vinit to the control electrode of the driving transistor T4 to turn on the driving transistor T4.
Data write and threshold compensation phases: the drive control unit 101 supplies a drive current to the light emitting device D. Specifically, the row scan signal GateA written in the pixel circuit, in response to which the scan switch transistor T2 is turned on, and at the same time, the threshold compensation transistor T3 is also turned on in response to the row scan signal GataA received by the gate electrode, thereby transmitting the data voltage signal Vdata _ I to the gate electrode of the driving transistor T4 via the threshold compensation transistor T3. At this time, the gate voltage of the driving transistor T4 is Vdata _ I + Vth, so that the threshold voltage is compensated, and the driving storage capacitor C1 stores the data voltage signal Vdata _ I. Since the driving transistor T4 is kept on by setting of the threshold compensation transistor T3 and the driving storage capacitor C1, but since the first emission control signal EM and the reset signal RST are both high level at this time, the first isolation transistor T9 and the isolation transistor T10 in the isolation unit 105 are both off, and the control electrode of the emission switch transistor T8 is kept at the first power signal due to the existence of the first isolation capacitor C3, the emission switch transistor T8 is controlled to be off, and the light emitting device D does not form a current path.
And a light emitting control stage: the LED lamp comprises a time control signal writing stage and a light emitting stage, wherein in the time control signal writing stage, an input control unit outputs an input light emitting time control signal Vdata _ T to an isolation unit; in the light emitting stage, the first isolation transistor T9 transmits a light emitting time control signal Vdata _ T to the driving control unit 101 in response to the first light emitting control signal EM to control the light emitting device to emit light.
Specifically, in the light emission control phase, first, the second light emission control signal GateB is at a low level in the time control signal writing phase, the input transistor T7 is turned on, and the light emission time control signal Vdata _ T is written into the input storage capacitor C2, but since the first light emission control signal EM is still at a high level, the written light emission time control signal Vdata _ T cannot be transmitted to the driving control unit, and the isolation unit 105 plays an isolation role. Thereafter, in the light emitting phase, the second light emitting control signal GataB is at a high level, the first light emitting control signal EM is turned to a low level, the first isolation transistor T9 is turned on, and the light emitting time control signal Vdata _ T stored in the input storage capacitor C2 is transmitted to the driving control unit 101, specifically, to the light emitting switching transistor T8 in the driving control unit 101. Meanwhile, since the first light emission control signal EM is at a low level, the first light emission control transistor T5 is turned on, and the driving transistor T4 is also turned on due to the holding action of the driving storage capacitor C1, and therefore, a current path for supplying a current to the light emitting device D exists in the driving control unit 101, and the light emitting device D emits light. In conjunction with the timing diagram in fig. 3, the specific light-emitting time is controlled by the first light-emitting control signal EM, and once the first light-emitting control signal EM goes high, an isolation is formed between the input control unit 103 and the drive control unit 101, so that the switching action of the light-emitting switching transistor T8 is in an off state.
Further specifically, a plurality of light emission control stages, that is, a combination of a plurality of time control signal writing stages and light emission stages may be included in one line scanning process. The first emission control signal EM comprises at least two active inputs, the emission control phase further comprising: the light emission time control signal Vdata _ T, which is input by the input control unit at the time control signal writing stage, is transmitted to the control electrode of the light emission switching transistor T8 of the driving control unit according to the first light emission control signal EM, so that the driving current signal is loaded to the first electrode of the light emitting device D and drives the light emitting device D to emit light.
Referring to fig. 3, in this example, a case where one line scanning process includes two light emission control stages is illustrated. As shown in the figure, when the first light emission control signal EM is turned to a high level after the first light emission is completed, and then the second light emission control signal GateB is turned to a low level, the input control unit 103 writes the light emission time control signal Vdata _ T, since the first isolation transistor T9 of the isolation unit 105 at this time is turned off under the control of the first light emission control signal EM, so that the isolation unit 105 generates an isolation action, the light emission time control signal Vdata _ T is held in the input storage capacitor C2, and when the first light emission control signal EM is turned to a low level, the light emission time control signal Vdata _ T stored in the input storage capacitor C2 is transmitted to the light emission switching transistor T8, and the light emitting device D emits light. It should be understood by those skilled in the art that the present application is not intended to limit the number of times that the light emitting device D emits light during the scanning process, and that more light emitting control stages may be designed as required to meet the requirement of adjusting the light emitting brightness of the light emitting device as the design criterion, and will not be described herein again.
In the above manner, by using the isolation unit, the phase after the pixel driving unit in the driving control unit completes the driving preparation is divided into the time control signal writing phase and the light emitting phase, so that the change of the light emitting time of the light emitting device caused by the change of the control electrode voltage of the driving transistor along with the change of the control electrode voltage of the driving transistor due to the coupling effect of Cgs when the control electrode voltage of the light emitting switch transistor changes in the writing process of the light emitting time control signal is avoided, the pixel gray scale control is more accurate, and the display effect is improved.
Another aspect of the present application also provides a display device including the pixel circuit according to the embodiment of the present application.
In the embodiment, the isolation unit is arranged in the pixel circuit of the display device, so that the isolated input light-emitting time control signal is isolated from the drive control unit, the gate voltage change of the drive transistor on a current path in the drive control unit caused by the writing of the light-emitting time control signal is avoided, and the false opening of the drive transistor is further avoided, so that the light-emitting device is ensured to normally emit light at a proper moment, the display panel displays according to the modulated gray scale, and the display device has a wide application prospect. The specific implementation manner of this embodiment is the same as that of the previous embodiment, and is not described herein again.
It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.
Claims (11)
1. A pixel circuit comprising a drive control unit, an input control unit, and an isolation unit, wherein:
the driving control unit includes a light emitting device for supplying a driving current to the light emitting device;
the isolation unit is used for isolating the light-emitting time control signal input by the input control unit from the drive control unit;
the input control unit is used for outputting the input light-emitting time control signal to the isolation unit and transmitting the input light-emitting time control signal to the drive control unit through the isolation unit so as to control the light-emitting time of the light-emitting device.
2. The pixel circuit according to claim 1, wherein the isolation unit comprises a first isolation transistor, a second isolation transistor, and a first isolation capacitor, wherein
A first electrode of the first isolation transistor is connected to a light-emitting time control signal output by the input control unit, a second electrode of the first isolation transistor is connected to a first node, a control electrode of the first isolation transistor is connected to a first light-emitting control signal, and the first node is a connection node between the isolation unit and the drive control unit;
a first pole of the second isolation transistor is connected to a first power supply signal, a second pole of the second isolation transistor is connected to the first node, and a control pole of the second isolation transistor is connected to a reset signal;
the first end of the first isolation capacitor is connected to the first node, and the second end of the first isolation capacitor is connected to a second power supply signal.
3. The pixel circuit according to claim 2, wherein the drive control unit comprises a light emitting unit and a pixel drive unit, wherein
The light emitting unit includes a light emitting switching transistor and a light emitting device;
the pixel driving unit is used for providing a driving current for the light-emitting device through the light-emitting switch transistor;
a first pole of the light-emitting switch transistor is connected to a driving current signal output by the pixel driving unit, a second pole of the light-emitting switch transistor is connected to the first pole of the light-emitting device, and a control pole of the light-emitting switch transistor is connected to the first node;
and the second pole of the light-emitting device is connected with a third power supply signal.
4. The pixel circuit according to claim 3, wherein the pixel driving unit comprises: scanning switch transistor, drive transistor, threshold compensation transistor, first reset transistor, first lighting control transistor and drive storage capacitor, wherein:
a first pole of the scanning switch transistor is connected with a data voltage signal, a second pole of the scanning switch transistor is connected to the second node, and a control pole of the scanning switch transistor is connected with a row scanning signal of the pixel circuit;
the first pole of the driving transistor is connected to the second node, the second pole of the driving transistor is connected to the first pole of the light-emitting switch transistor, and the control pole of the driving transistor is connected to the third node;
a first pole of the threshold compensation transistor is connected to the third node, a second pole of the threshold compensation transistor is connected to a second pole of the driving transistor, and a control pole of the threshold compensation transistor is connected to a row scanning signal of the pixel circuit;
a first pole of the first reset transistor is connected to the third node, a second pole of the first reset transistor is connected to a fourth power supply signal, and a control pole of the first reset transistor is connected to a reset signal;
a first pole of the first light-emitting control transistor is connected to a fifth power supply signal, a second pole of the first light-emitting control transistor is connected to the second node, and a control pole of the first light-emitting control transistor is connected to the first light-emitting control signal;
the first end of the driving storage capacitor is connected to the fourth node, and the second end of the driving storage capacitor is connected to the third node.
5. The pixel circuit according to claim 2, wherein the input control unit comprises an input transistor and an input storage capacitor, wherein:
the first pole of the input transistor is connected to the light-emitting time control signal, the second pole of the input transistor is connected to the first pole of the first isolation transistor of the isolation unit, and the control pole of the input transistor is connected to the second light-emitting control signal;
the first end of the input storage capacitor is connected to the first pole of the first isolation transistor of the isolation unit, and the second end of the input storage capacitor is connected to a second power supply signal.
6. A display device comprising the pixel circuit according to any one of claims 1 to 5.
7. A driving method using the pixel circuit according to any one of claims 1 to 5, comprising:
the isolation unit isolates a light-emitting time control signal input by the input control unit from the drive control unit, and the drive control unit comprises a light-emitting device;
the driving control unit supplies a driving current to the light emitting device;
the input control unit outputs an input light-emitting time control signal to the isolation unit and transmits the input light-emitting time control signal to the drive control unit through the isolation unit so as to control the light-emitting time of the light-emitting device.
8. The driving method according to claim 7, wherein the isolation unit includes a first isolation transistor, a second isolation transistor, and a first isolation capacitor, wherein a first pole of the first isolation transistor is connected to the light-emitting time control signal output by the input control unit, a second pole of the first isolation transistor is connected to a first node, a control pole of the first isolation transistor is connected to the first light-emitting control signal, and the first node is a connection node between the isolation unit and the driving control unit; a first pole of the second isolation transistor is connected to a first power supply signal, a second pole of the second isolation transistor is connected to the first node, and a control pole of the second isolation transistor is connected to a reset signal; the first end of the first isolation capacitor is connected to the first node, and the second end of the first isolation capacitor is connected to a second power supply signal;
the driving method includes:
a reset stage: the second isolation transistor outputs a first power supply signal to the drive control unit in response to a reset signal;
data write and threshold compensation phases: the driving control unit supplies a driving current to the light emitting device;
and a light emitting control stage: the method comprises the following steps:
time control signal writing stage: the input control unit outputs the input light-emitting time control signal to the isolation unit;
a light emitting stage: the first isolation transistor transmits a light emitting time control signal to the driving control unit in response to a first light emitting control signal to control the light emitting device to emit light.
9. The driving method according to claim 8,
the driving control unit comprises a light emitting unit and a pixel driving unit, the light emitting unit comprises a light emitting switch transistor and a light emitting device, wherein a first pole of the light emitting switch transistor is connected to a driving current signal output by the pixel driving unit, a second pole of the light emitting switch transistor is connected to the first pole of the light emitting device, and a control pole of the light emitting switch transistor is connected to the first node; a second pole of the light emitting device is connected to a third power supply signal;
the pixel driving unit includes: the pixel circuit comprises a scanning switch transistor, a driving transistor, a threshold compensation transistor, a first reset transistor, a first light-emitting control transistor and a driving storage capacitor, wherein a first pole of the scanning switch transistor is connected with a data voltage signal, a second pole of the scanning switch transistor is connected to the second node, and a control pole of the scanning switch transistor is connected with a row scanning signal of the pixel circuit; the first pole of the driving transistor is connected to the second node, the second pole of the driving transistor is connected to the first pole of the light-emitting switch transistor, and the control pole of the driving transistor is connected to the third node; a first pole of the threshold compensation transistor is connected to the third node, a second pole of the threshold compensation transistor is connected to the second pole of the driving transistor, and a control pole of the threshold compensation transistor is connected to a row scanning signal of the pixel circuit; a first pole of the first reset transistor is connected to the third node, a second pole of the first reset transistor is connected to a fourth power supply signal, and a control pole of the first reset transistor is connected to a reset signal; a first pole of the first light-emitting control transistor is connected to a fifth power supply signal, a second pole of the first light-emitting control transistor is connected to the second node, and a control pole of the first light-emitting control transistor is connected to the first light-emitting control signal; a first end of the driving storage capacitor is connected to a fifth power supply signal, and a second end of the driving storage capacitor is connected to the third node;
the reset phase further comprises: the second isolation transistor outputs a first power supply signal to a control electrode of the light emitting switch transistor in response to a reset signal, the first reset transistor discharges the driving storage capacitor in response to a reset signal RST, and outputs a fourth power supply signal to a control electrode of the driving transistor to turn on the driving transistor;
the data write and threshold compensation phase further comprises: the scan switching transistor transmits an input data voltage signal to a first pole of the driving transistor in response to a row scan signal of the pixel circuit; the threshold compensation transistor compensates a threshold voltage of the driving transistor in response to a row scan signal of the pixel circuit; the driving transistor is switched on, the data voltage signal is transmitted to the grid electrode of the driving transistor through the threshold compensation transistor, and the storage capacitor is driven to store the data voltage signal; the first light-emitting control transistor provides a fifth power supply signal to the driving transistor in response to a first light-emitting control signal to form a current path, and the driving transistor generates a driving current signal and transmits the driving current signal to the first pole of the light-emitting switch transistor;
the timing control signal writing phase further comprises: the input control unit outputs an input light-emitting time control signal to a first pole of a first isolation transistor of the isolation unit;
the lighting phase further comprises: the first isolation transistor transmits a light emitting time control signal to a control electrode of a light emitting switching transistor of the driving control unit in response to a first light emitting control signal, so that the driving current signal is applied to a first electrode of the light emitting device and drives the light emitting device to emit light.
10. The driving method according to claim 9, wherein the input control unit includes an input transistor and an input storage capacitor, wherein: the first pole of the input transistor is connected to the light-emitting time control signal, the second pole of the input transistor is connected to the first pole of the first isolation transistor of the isolation unit, and the control pole of the input transistor is connected to the second light-emitting control signal; the first end of the input storage capacitor is connected to the first pole of the first isolation transistor of the isolation unit, and the second end of the input storage capacitor is connected to a second power supply signal;
the timing control signal writing phase further comprises: the input transistor stores the light emission time control signal in the input storage capacitor in response to a second light emission control signal to transmit the light emission time control signal to a first pole of a first isolation transistor of an isolation unit.
11. The driving method according to any one of claims 8 to 10, wherein the first lighting control signal comprises at least two active inputs, the lighting control phase further comprising:
and transmitting the light emitting time control signal to a control electrode of a light emitting switch transistor of the driving control unit according to the first light emitting control signal, so that the driving current signal is loaded to a first electrode of the light emitting device and drives the light emitting device to emit light, wherein the time control signal is the light emitting time control signal input by the input control unit in the time control signal writing stage.
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