CN114255691B - Pixel circuit, driving method thereof and display device - Google Patents
Pixel circuit, driving method thereof and display device Download PDFInfo
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- CN114255691B CN114255691B CN202011014626.XA CN202011014626A CN114255691B CN 114255691 B CN114255691 B CN 114255691B CN 202011014626 A CN202011014626 A CN 202011014626A CN 114255691 B CN114255691 B CN 114255691B
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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 and 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 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 to isolate the light-emitting time control signal which is input in an isolated manner from the drive control unit, so that the change of the grid voltage of the drive transistor on the current path in the drive control unit caused by the writing of the signal is avoided, the light-emitting device is ensured to emit light normally at the design moment, and the application prospect is wide.
Description
Technical Field
The present invention relates to the field of display technologies, and in particular, to a pixel circuit, a driving method thereof, and a display device.
Background
Micro LEDs are a new generation of display technology, and have higher brightness, better luminous efficiency and lower power consumption than the existing OLED technology, so the excellent characteristics of the micro LEDs can enable the micro LEDs to be applied to televisions, iPhones and iPads. Meanwhile, as a self-luminous device, a micro led has a luminous efficiency that decreases with a decrease in current density at a low current density. Different gray scales of the OLED display are realized by driving the OLED device with different current densities to emit light with different brightness. However, when the micro led display uses only a variable current density to realize brightness of different gray scales, light emission efficiency is low and power consumption is high due to low current density at low gray scales.
In order to make the mirco led operate at a high current density, as shown in fig. 1, which is a schematic diagram of a micro led pixel driving circuit in the prior art, a PWM control module is introduced on the current path to control the on time of the current path. When vdata_t of PWM is written, the gate voltage of DTFT (Drive Thin Film Transistor, driving thin film transistor) T4 therein is changed due to the capacitive coupling effect, the gate of T8 is in a floating state before gate b is turned on, vdata_t is written after gate b is turned on, the gate voltage of T8 is changed, the drain voltage of T4 is changed due to the coupling effect of T8 Cgs, and the gate voltage of T4 is changed due to the coupling effect of Cgd, thereby disabling the light emitting element from being 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 and 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 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 alternative embodiments, the isolation unit includes a first isolation transistor, a second isolation transistor, and a first isolation capacitor, wherein
The first pole of the first isolation transistor is connected with the light-emitting time control signal output by the input control unit, the second pole is connected to the first node, the control pole is connected with 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 electrode of the second isolation transistor is connected with a first power supply signal, a second electrode of the second isolation transistor is connected to the first node, and a control electrode of the second isolation transistor is connected with a reset signal;
the first end of the first isolation capacitor is connected to the first node, and the second end is connected to the second power supply signal.
In some alternative embodiments, the driving control unit includes a light emitting unit and a pixel driving unit, wherein the light emitting unit includes 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 with 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 with a third power supply signal.
In some alternative embodiments, the pixel driving unit includes: a scan switching transistor, a driving transistor, a threshold compensation transistor, a first reset transistor, a first light emitting control transistor, and a driving storage capacitor, wherein:
the first electrode of the scanning switch transistor is connected with a data voltage signal, the second electrode is connected to the second node, and the control electrode is connected with a line scanning signal of the pixel circuit;
the first electrode of the driving transistor is connected to the second node, the second electrode is connected to the first electrode of the light-emitting switch transistor, and the control electrode 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;
the first electrode of the first reset transistor is connected to the third node, the second electrode is connected to a fourth power supply signal, and the control electrode is connected to a reset signal;
a first electrode of the first light-emitting control transistor is connected with a fifth power supply signal, a second electrode of the first light-emitting control transistor is connected to the second node, and a control electrode of the first light-emitting control transistor is connected with the first light-emitting control signal;
the first end of the driving storage capacitor is connected to the fourth node, and the second end is connected to the third node.
In some alternative embodiments, the input control unit includes an input transistor and an input storage capacitor, wherein:
the first electrode of the input transistor is connected with a light-emitting time control signal, the second electrode of the input transistor is connected to the first electrode of the first isolation transistor of the isolation unit, and the control electrode 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 is connected to the second power supply signal.
A second aspect of the present application provides a display device comprising a pixel circuit as described in the first aspect of the present application.
A third aspect of the present application provides a driving method of the pixel circuit described in 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 light emitting time control signal to the drive control unit through the isolation unit 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 is connected to a first node, the control pole 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 electrode of the second isolation transistor is connected with a first power supply signal, a second electrode of the second isolation transistor is connected to the first node, and a control electrode of the second isolation transistor is connected with 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:
and (3) a reset stage: the second isolation transistor outputs a first power supply signal to the drive control unit in response to the reset signal;
data writing and threshold compensation phase: the driving control unit supplies a driving current to the light emitting device;
and a light emission control stage: comprising the following steps:
time control signal writing phase: the input control unit outputs the input light-emitting time control signal to the isolation unit;
and (3) 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 of the present invention,
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 with a driving current signal output by the pixel driving unit, a second pole is connected to a first pole of the light emitting device, and a control pole 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 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 electrode of the driving transistor is connected to the second node, the second electrode is connected to the first electrode of the light-emitting switch transistor, and the control electrode 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 the row scanning signal of the pixel circuit; the first electrode of the first reset transistor is connected to the third node, the second electrode is connected to a fourth power supply signal, and the control electrode is connected to a reset signal; a first electrode of the first light-emitting control transistor is connected with a fifth power supply signal, a second electrode of the first light-emitting control transistor is connected to the second node, and a control electrode of the first light-emitting control transistor is connected with the first light-emitting control signal; the first end of the driving storage capacitor is connected with a fifth power supply signal, and the second end of the driving storage capacitor is connected to a third node;
the reset phase further comprises: the second isolation transistor outputs a first power supply signal to the control electrode of the light-emitting switch transistor in response to a reset signal, the first reset transistor discharges the drive storage capacitor in response to a reset signal RST, and outputs a fourth power supply signal to the control electrode of the drive transistor to turn on the drive transistor;
the data writing and threshold compensation phase further comprises: the scan switching transistor transmits an input data voltage signal to a first electrode 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 scanning signal of the pixel circuit; the drive transistor is conducted to transmit a data voltage signal to the grid electrode of the drive transistor through the threshold compensation transistor, and the storage capacitor is driven to store the data voltage signal; the first light-emitting control transistor responds to the first light-emitting control signal to provide a fifth power supply signal for the driving transistor 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 switching transistor;
the time control signal writing phase further comprises: 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 emission time control signal to a control electrode of the light emission switching transistor of the driving control unit in response to the first light emission control signal, so that a driving current signal is loaded 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 includes an input transistor and an input storage capacitor, wherein: the first electrode of the input transistor is connected with a light-emitting time control signal, the second electrode of the input transistor is connected to the first electrode of the first isolation transistor of the isolation unit, and the control electrode 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;
the time control signal writing phase further comprises: 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 the first isolation transistor of the isolation unit.
In some alternative 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 the light-emitting switch transistor of the drive control unit according to the first light-emitting control signal, so that a drive 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 a time control signal writing stage.
The beneficial effects of the invention are as follows:
the pixel circuit, the driving method thereof and the display device are formulated aiming at the existing problems at present, the input light-emitting time control signal is isolated from the driving control unit by arranging the isolation unit between the driving control unit and the input control unit, the grid voltage change of the driving transistor on the current path in the driving control unit is avoided when the light-emitting time control signal is written, and further the false start of the driving transistor is avoided, so that the light-emitting device is ensured to emit light normally at the design moment, the display panel can display according to the modulated gray scale accurately, and the display device has wide application prospect.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic circuit schematic 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
For a clearer description of the present application, the present application is further described below with reference to preferred embodiments and the accompanying drawings. Like parts in the drawings are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is intended to be illustrative, and not restrictive, and that this invention is not to be limited to the specific embodiments shown.
It should be noted that, as used herein, "on … …", "formed on … …", and "disposed on … …" may mean that one layer is directly formed or disposed on another layer, or that one layer is indirectly formed or disposed on another layer, i.e., that other layers are present between the two layers. In this document, unless otherwise indicated, the term "in the same layer" is used to mean that two layers, components, members, elements, or portions may be formed by the same patterning process, and that the two layers, components, members, elements, or portions are generally formed of the same material. In this context, unless otherwise indicated, the expression "patterning process" generally includes the steps of coating of photoresist, exposure, development, etching, stripping of photoresist, and the like. The expression "one patterning process" means a process of forming a patterned layer, feature, component, etc. using a single mask.
It should be further noted that, in the embodiment of the present application, the transistors are P-type transistors, but those skilled in the art will understand that the transistors in the present application may be N-type transistors, and when they are N-type transistors, only the signal level of the control electrode of the input transistor needs to be properly adjusted.
As shown in fig. 2, an embodiment of the present application provides a pixel circuit, which is characterized by including 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 and 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 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 setting the isolation unit between the drive control unit and the input control unit, the input light-emitting time control signal is isolated from the drive control unit, so that the gate voltage of the driving transistor on the current path in the drive control unit is prevented from changing when the light-emitting time control signal is written, and further, the driving transistor is prevented from being turned on by mistake, thereby ensuring that the light-emitting device emits light normally at the design time, and the display panel can display according to the modulated gray scale accurately, and has a 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 drive control unit comprises a light emitting device D for providing a drive current to the light emitting device D. The light emitting device may alternatively 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, where 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 light emitting time control signal vdata_t to the driving control unit 101 via 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 the first node N1, a control pole is connected to the first light emission control signal EM, the first node N1 is a connection node between the isolation unit 105 and the drive 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 drive control unit in response to the first light emission control signal EM; a first pole of the second isolation transistor T10 is connected to the first power supply signal VGH, a second pole is connected to the first node N1, a 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, that is, pulls the control pole of the light emitting transistor T8 high through the first power supply 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 electric potential of the gate of the light emitting transistor T8, that is, maintaining the first power signal VGH that pulls the control electrode of the light emitting transistor T8 high.
Specifically, the driving 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 is configured to supply a driving current to the light emitting device D through the light emitting switching transistor T8. The first pole of the light emitting switching transistor T8 is connected to the driving current signal output from the pixel driving unit 101-2, the second pole is connected to the first pole of the light emitting device D, and the control pole is connected to the first node N1 to receive the light emitting time control signal vdata_t transmitted by 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 electrode 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 switching transistor T2, a driving transistor T4, a threshold compensating transistor T3, a first reset transistor T1, a first light emitting control transistor T5, and a driving storage capacitor C1, wherein a first electrode of the scan switching transistor T2 is connected to a data voltage signal vdata_i, a second electrode is connected to a second node N2, a control electrode is connected to a row scan signal GateA of the pixel circuit, and the scan switching transistor T2 transmits the data voltage signal vdata_i in response to an input nth row scan signal GataA (where N is a positive integer, and a maximum value is a total number of rows of pixels to be scanned). The driving transistor T4 has a first pole connected to the second node N2, a second pole connected to the first pole of the light emitting switching transistor T8, and a control pole 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 by the scan switching transistor T2. The first pole of the threshold compensation transistor T3 is connected to the third node N3, the second pole is connected to the second pole of the driving transistor T4, and the control pole is 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, since the driving transistor T4 is turned on and the threshold compensating transistor T3 is turned on, the data voltage signal vdata_i is transmitted to the gate electrode of the driving transistor T4. The first reset transistor T1 has a first pole connected to the third node N3, a second pole connected to the fourth power signal Vinit, and a control pole connected to the reset signal RST, and the first reset transistor T1 discharges the driving storage capacitor C1 through the fourth power signal Vinit in response to the reset signal RST, and transmits the fourth power signal Vinit to the control pole of the driving transistor T4 to turn on the driving transistor T4. The first electrode of the first light emitting control transistor T5 is connected to the fifth power signal Vdd, the second electrode is connected to the second node N2, the control electrode is connected to the first light emitting control signal EM, and the first light emitting control transistor T5 provides the fifth power signal Vdd to the driving transistor T4 in response to the first light emitting control signal EM to form a current path to transmit a driving current signal to the first electrode of the light emitting switching transistor T8. The first terminal of the driving storage capacitor C1 is connected to the 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 emitting control transistor T5, and the second terminal is connected to the third node N3, and the driving storage capacitor C1 is used for storing 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 first electrode of the input transistor T7 is connected to the light-emitting time control signal vdata_t, the second electrode is connected to the first electrode of the first isolation transistor T9 of the isolation unit 105, the control electrode is connected to the second light-emitting control signal GateB, and the input transistor T7 transmits the light-emitting time control signal vdata_t to the isolation unit 105 in response to the second light-emitting control signal GateB. The first end of the input storage capacitor C2 is connected to the first pole of the first isolation transistor T9 of the isolation unit, the second end 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.
By providing the isolation unit 105 between the input control unit 103 and the drive control unit 101, the pixel circuit according to the embodiment of the present application can isolate the light emission time control signal vdata_t input by the input control unit 103 from the drive control unit, thereby avoiding the change of the gate voltage of the drive transistor on the current path in the drive control unit 101 when writing the light emission time control signal vdata_t.
In order to clarify the operation principle of the pixel circuit in the embodiment of the present application, a driving method of the pixel circuit in the embodiment of the present application is described below, and a specific process is described with reference to fig. 2 and a timing chart of fig. 3.
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 light emitting time control signal to the drive control unit through the isolation unit to control the light emitting time of the light emitting device.
Specifically, referring to fig. 3, a driving method of the pixel circuit of the embodiment of the present application is described with reference to a pixel circuit including the driving control unit 101, the input control unit 103, and the isolation unit 105 shown in fig. 2, and includes:
and (3) 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, specifically, 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 by the control electrode, thereby outputting the first power supply signal VGH to the control electrode of the light emitting switching transistor T8. It will be appreciated 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, the light emitting switching transistor T8 is turned off, the light emitting device D does not obtain any driving current, and the first power signal VGH charges the first isolation capacitor C3. Further, in the reset stage, in response to the reset signal RST, the first reset transistor T1 is turned on, discharges the driving storage capacitor C1 and outputs the fourth power supply signal Vinit to the gate of the driving transistor T4 to turn on the driving transistor T4.
Data writing and threshold compensation phase: the drive control unit 101 supplies a drive current to the light emitting device D. Specifically, the scan switching transistor T2 is turned on in response to the row scan signal GateA written into the pixel circuit, and the threshold compensation transistor T3 is also turned on in response to the row scan signal GataA received by the control electrode, thereby transmitting the data voltage signal vdata_i to the control 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 the setting of the threshold compensation transistor T3 and the driving storage capacitor C1, but since the first light emitting control signal EM and the reset signal RST are both at high level at this time, the first isolation transistor T9 and the isolation transistor T10 in the isolation unit 105 are both in an off state, and since the first isolation capacitor C3 is present, the control electrode of the light emitting switching transistor T8 is kept at the first power supply signal, the light emitting switching transistor T8 is controlled to be turned off, and the light emitting device D does not form a current path.
And a light emission control stage: the light emitting device 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 the 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 stage, first, the second light emission control signal GateB is at a low level in the time control signal writing stage, the input transistor T7 is turned on, 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 into the driving control unit, and the isolation unit 105 plays an isolating role. Thereafter, in the light emitting stage, 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 emitting control signal EM is at a low level, the first light emitting control transistor T5 is turned on, and the driving transistor T4 is also turned on due to the holding function of the driving storage capacitor C1, and thus, there is a current path in the driving control unit 101 to supply current to the light emitting device D, and the light emitting device D emits light. In conjunction with the timing chart in fig. 3, the specific light emission time is controlled by the first light emission control signal EM, and once the first light emission control signal EM goes high level, isolation is formed between the input control unit 103 and the driving control unit 101, so that the switching action of the light emission switching transistor T8 is in an off state.
Further specifically, a plurality of light emission control phases may be included in one line scanning process, i.e., a combination of a plurality of time control signal writing phases and a light emission phase. The first light emission control signal EM comprises at least two active inputs, the light emission control phase further comprising: the light emission time control signal vdata_t 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, and the time control signal vdata_t is input by the input control unit in the time control signal writing stage.
Referring to fig. 3, in this example, a case where one line scanning process includes two light emission control phases is exemplified. As shown in the figure, when the first light emission is completed, the first light emission control signal EM is turned to a high level, 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 at this time of the isolation unit 105 is turned off under the control of the first light emission control signal EM, so that the isolation unit 105 generates an isolation effect, 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 the light emitting device D emits light in the process of scanning again, and more times of light emission control stages may be designed as required to satisfy the adjustment of the light emission brightness of the light emitting device as a design criterion, which is not described herein.
In the above manner, the isolation unit is utilized to divide the stage of the pixel driving unit in the driving control unit after finishing driving preparation into the time control signal writing stage and the light-emitting stage, 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 due to the coupling effect of Cgs when the control electrode voltage of the light-emitting switching transistor changes in the writing process of the light-emitting time control signal is avoided, the gray scale control of the pixel is more accurate, and the display effect is improved.
Another aspect of the present application also provides a display device, including a pixel circuit described in the embodiments of the present application.
In this embodiment, by setting the isolation unit in the pixel circuit of the display device, the light-emitting time control signal input by isolation is isolated from the drive control unit, so that the gate voltage of the drive transistor on the current path in the drive control unit is prevented from changing when the light-emitting time control signal is written, and further, the error starting of the drive transistor is prevented, thereby ensuring that the light-emitting device emits light normally at a proper time, and the display panel displays according to the modulated gray scale, and has a wide application prospect. The specific implementation manner of this embodiment is the same as that of the foregoing embodiment, and will not be described herein.
It should be understood that the foregoing examples of the present invention are provided merely for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention, and that various other changes and modifications may be made therein by one skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims.
Claims (10)
1. A pixel circuit comprising a drive control unit, an input control unit, and an isolation unit, wherein:
the driving control unit comprises a light emitting device for providing 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 and the drive control unit;
the input control unit is used for outputting an input light-emitting time control signal to the isolation unit and transmitting the signal to the drive control unit through the isolation unit so as to control the light-emitting time of the light-emitting device;
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 with 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 with the first light-emitting control signal, and the first node is a connection node of the isolation unit and the drive control unit; 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;
a first pole of the second isolation transistor is connected with 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 with a reset signal; the second isolation transistor resets the control electrode of the light emitting transistor in the driving control unit in response to the reset signal, namely, the control electrode of the light emitting transistor is pulled high through the first power supply signal;
a first end of the first isolation capacitor is connected to the first node, and a second end of the first isolation capacitor is connected to a second power supply signal; the first isolation capacitor is used for storing and maintaining the potential of the grid electrode of the light emitting transistor.
2. The pixel circuit according to claim 1, wherein the drive control unit includes a light emitting unit and a pixel driving unit, wherein
The light emitting unit comprises a light emitting switch transistor and a light emitting device;
the pixel driving unit is used for providing driving current for the light emitting device through the light emitting switching transistor;
a first electrode of the light-emitting switch transistor is connected with 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 the first node;
and a second electrode of the light emitting device is connected with a third power supply signal.
3. The pixel circuit according to claim 2, wherein the pixel driving unit includes: a scan switching transistor, a driving transistor, a threshold compensation transistor, a first reset transistor, a first light emitting control transistor, and a driving storage capacitor, wherein:
the first electrode of the scanning switch transistor is connected with a data voltage signal, the second electrode of the scanning switch transistor is connected to the second node, and the control electrode of the scanning switch transistor is connected with a row scanning signal of the pixel circuit;
the first electrode of the driving transistor is connected to a second node, the second electrode is connected to the first electrode of the light-emitting switch transistor, and the control electrode is connected to a 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 is connected with a fourth power supply signal, and a control pole is connected with a reset signal;
a first electrode of the first light-emitting control transistor is connected with a fifth power supply signal, a second electrode of the first light-emitting control transistor is connected to a second node, and a control electrode of the first light-emitting control transistor is connected with a 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.
4. The pixel circuit of claim 1, wherein the input control unit comprises an input transistor and an input storage capacitor, wherein:
the first electrode of the input transistor is connected with the light-emitting time control signal, the second electrode of the input transistor is connected to the first electrode of the first isolation transistor of the isolation unit, and the control electrode of the input transistor is connected with 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 the second power supply signal.
5. A display device comprising the pixel circuit according to any one of claims 1 to 4.
6. A driving method using the pixel circuit according to any one of claims 1 to 4, comprising:
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 an input light emitting time control signal to the isolation unit and transmits the light emitting time control signal to the driving control unit through the isolation unit to control the light emitting time of the light emitting device.
7. The driving method according to claim 6, 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 emission time control signal output by the input control unit, a second pole is connected to a first node, a control pole is connected to the first light emission 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 with 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 with a reset signal; a first end of the first isolation capacitor is connected to the first node, and a second end of the first isolation capacitor is connected to a second power supply signal;
the driving method includes:
and (3) 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 writing and threshold compensation phase: the driving control unit supplies a driving current to the light emitting device;
and a light emission control stage: comprising the following steps:
time control signal writing phase: the input control unit outputs the input light-emitting time control signal to the isolation unit;
and (3) a light-emitting stage: the first isolation transistor transmits a light emission time control signal to the driving control unit in response to a first light emission control signal to control the light emitting device to emit light.
8. The driving method according to claim 7, wherein,
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 with 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 the first node; a second electrode 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 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 electrode of the driving transistor is connected to a second node, the second electrode is connected to the first electrode of the light-emitting switch transistor, and the control electrode is connected to a 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 is connected with a fourth power supply signal, and a control pole is connected with a reset signal; a first electrode of the first light-emitting control transistor is connected with a fifth power supply signal, a second electrode of the first light-emitting control transistor is connected to a second node, and a control electrode of the first light-emitting control transistor is connected with a first light-emitting control signal; a first end of the driving storage capacitor is connected with 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 the 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 the control electrode of the driving transistor to turn on the driving transistor;
the data writing 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 scanning signal of the pixel circuit; the drive transistor is conducted to transmit a data voltage signal to the grid electrode of the drive 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 a first pole of the light emitting switching transistor;
the time control signal writing phase further comprises: the input control unit outputs an input light emission 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 emission time control signal to a control electrode of a light emission switching transistor of the driving control unit in response to a first light emission 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.
9. The driving method according to claim 8, wherein the input control unit includes an input transistor and an input storage capacitor, wherein: the first electrode of the input transistor is connected with the light-emitting time control signal, the second electrode of the input transistor is connected to the first electrode of the first isolation transistor of the isolation unit, and the control electrode of the input transistor is connected with 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 the second power supply signal;
the time 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.
10. The driving method according to any one of claims 7-9, wherein the first light emission control signal comprises at least two active inputs, the light emission 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 writing stage of the time control signal.
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| CN110021263B (en) * | 2018-07-05 | 2020-12-22 | 京东方科技集团股份有限公司 | Pixel circuit, driving method thereof and display panel |
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| CN109920371B (en) * | 2019-04-26 | 2021-01-29 | 京东方科技集团股份有限公司 | Pixel circuit, driving method thereof and display device |
| CN109979378B (en) * | 2019-05-15 | 2020-12-04 | 京东方科技集团股份有限公司 | Pixel driving circuit and display panel |
| CN111540304A (en) * | 2020-01-20 | 2020-08-14 | 重庆康佳光电技术研究院有限公司 | Gray scale regulating circuit and display device |
| CN111477163B (en) * | 2020-04-21 | 2021-09-28 | 京东方科技集团股份有限公司 | Pixel driving circuit, driving method thereof and display panel |
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