CN105489166A - Pixel circuit and display device - Google Patents
Pixel circuit and display device Download PDFInfo
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- CN105489166A CN105489166A CN201610077714.1A CN201610077714A CN105489166A CN 105489166 A CN105489166 A CN 105489166A CN 201610077714 A CN201610077714 A CN 201610077714A CN 105489166 A CN105489166 A CN 105489166A
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- G—PHYSICS
- 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]
- G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
- G09G3/3225—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
- G09G3/3233—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the current through the light-emitting element
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Abstract
The invention discloses a pixel circuit and a display device. The pixel circuit comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a driving transistor, a first capacitor, and a second capacitor. According to the pixel circuit and the display device, the driving current and the driving transistor are finally prevented from being influenced by threshold voltage via cooperative driving of the transistors and the two capacitors, the influence of adverse factors is eliminated, the problem of non-uniform light emission of the display device is effectively improved, and the light-emitting uniformity and the display effect of the display device are improved.
Description
Technical Field
The invention relates to the technical field of organic light emitting display, in particular to a pixel circuit and a display device.
Background
With the development of multimedia, an Organic Light Emitting Diode (OLED) display device has attracted attention in the market of display devices with advantages of simple structure, excellent operating temperature, contrast, viewing angle, and the like. The organic light emitting diode display device includes a passive matrix OLED display device and an active matrix OLED display device, which are widely used due to low power consumption. In practical use, the organic light emitting diode display device is found to have a phenomenon of non-uniform light emission.
Disclosure of Invention
In view of the above, the present invention provides a pixel circuit and a display device, which can eliminate the influence of the threshold voltage by compensating the threshold voltage of the driving transistor for driving the light emitting element, thereby eliminating the non-uniform light emission of the display device.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
a pixel circuit for driving a light emitting element, comprising: the driving circuit comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a driving transistor, a first capacitor and a second capacitor;
the first transistor is controlled by a first driving signal for transmitting a driving current from the driving transistor to the light emitting element;
the second transistor is controlled by a second driving signal and is used for controlling the grid electrode of the driving transistor and the drain electrode of the driving transistor to be electrically connected or insulated;
the third transistor is controlled by a third driving signal and is used for transmitting a reset voltage to the grid electrode of the driving transistor so as to drive the driving transistor to be conducted;
the fourth transistor is controlled by a fourth driving signal and is used for transmitting a reference voltage to the first plate of the first capacitor, and the second plate of the first capacitor is electrically connected with the grid electrode of the driving transistor;
the fifth transistor is controlled by a fifth driving signal and is used for transmitting a data voltage to the first plate of the first capacitor;
the driving transistor is used for determining the magnitude of the driving current, the source electrode of the driving transistor and the first plate of the second capacitor are both connected with a power supply voltage, and the second plate of the second capacitor is electrically connected with the grid electrode of the driving transistor.
Optionally, a gate of the first transistor is connected to the first driving signal, a first electrode of the first transistor is electrically connected to a drain of the driving transistor, and a second electrode of the first transistor is electrically connected to the light emitting element;
the grid electrode of the second transistor is connected with the second driving signal, the first electrode of the second transistor is electrically connected with the drain electrode of the driving transistor, and the second electrode of the second transistor is electrically connected with the grid electrode of the driving transistor;
the grid electrode of the third transistor is connected with the third driving signal, the first electrode of the third transistor is connected with the reset voltage, and the second electrode of the third transistor is electrically connected with the grid electrode of the driving transistor;
a grid electrode of the fourth transistor is connected with the fourth driving signal, a first electrode of the fourth transistor is connected with the reference voltage, and a second electrode of the fourth transistor is electrically connected with a first polar plate of the first capacitor;
the grid electrode of the fifth transistor is connected with the fifth driving signal, the first electrode of the fifth transistor is connected with the data voltage, and the second electrode of the fifth transistor is electrically connected with the first polar plate of the first capacitor.
Optionally, the data voltage is greater than the reference voltage, and the reference voltage is not greater than the power supply voltage.
Optionally, the reference voltage is the same as the power supply voltage, and the reference voltage and the power supply voltage are output from the same voltage end;
or, the reference voltage is smaller than the power supply voltage, and the reference voltage and the power supply voltage are output by different voltage ends.
Optionally, the driving method of the pixel circuit includes three stages, namely an initialization stage, a threshold voltage detection stage and a light emitting stage, wherein,
in the initialization stage, the third driving signal drives the third transistor to be turned on, the fourth driving signal drives the fourth transistor to be turned off, and the fifth driving signal drives the fifth transistor to be turned on;
in the threshold voltage detection stage, the first driving signal drives the first transistor to be turned off, the second driving signal drives the second transistor to be turned on, the third driving signal drives the third transistor to be turned off, the fourth driving signal drives the fourth transistor to be turned off, and the fifth driving signal drives the fifth transistor to be turned on;
in the light emitting stage, the first driving signal drives the first transistor to be turned on, the second driving signal drives the second transistor to be turned off, the third driving signal drives the third transistor to be turned off, the fourth driving signal drives the fourth transistor to be turned on, and the fifth driving signal drives the fifth transistor to be turned off.
Optionally, the second driving signal and the fifth driving signal are the same, and the second driving signal and the fifth driving signal are output from the same driving signal terminal.
Optionally, the first driving signal and the fourth driving signal are the same, and the first driving signal and the fourth driving signal are output from the same driving signal terminal.
Optionally, before the first driving signal in the light emitting phase drives the first transistor to be turned on, the light emitting phase further includes:
after the first driving signal drives the first transistor to be turned off for a preset time period, the first driving signal drives the first transistor to be turned on;
the second driving signal drives the second transistor to be turned off, the third driving signal drives the third transistor to be turned off, the fourth driving signal drives the fourth transistor to be turned on, and the fifth driving signal drives the fifth transistor to be turned off.
Optionally, the first transistor, the second transistor, the third transistor, the fourth transistor, the fifth transistor, and the driving transistor are all P-type transistors.
Correspondingly, the invention also provides a display device which comprises the pixel circuit.
Compared with the prior art, the technical scheme provided by the invention at least has the following advantages:
the invention provides a pixel circuit and a display device, comprising: the driving circuit comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a driving transistor, a first capacitor and a second capacitor; through the matched driving between each transistor and the two capacitors, the driving current and the threshold voltage of the driving transistor are unrelated, the influence of adverse factors is eliminated, the problem of uneven light emission of the display device is effectively solved, and the light emission uniformity and the display effect of the display device are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a pixel circuit according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of another pixel circuit according to an embodiment of the present disclosure;
FIG. 3 is a timing diagram of driving signals according to an embodiment of the present disclosure;
fig. 4 is a schematic structural diagram of another pixel circuit according to an embodiment of the present disclosure;
FIG. 5 is a timing diagram of another driving signal according to an embodiment of the present disclosure;
fig. 6 is a schematic structural diagram of another pixel circuit according to an embodiment of the present disclosure;
fig. 7 is a schematic structural diagram of another pixel circuit according to an embodiment of the present disclosure.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As described in the background art, in practical use, it is found that the organic light emitting diode display device has a phenomenon of non-uniform light emission. In the conventional organic light emitting diode display device, the pixel circuit of the organic light emitting diode display device cannot compensate the threshold voltage of the driving transistor, so that the threshold voltage of the driving transistor affects the driving current, and the driving transistors of different pixel units have different threshold voltages due to process reasons, so that the luminance of different pixel units is different, the light emission of the display device is uneven, and the light emission effect of the display device is reduced.
In view of this, embodiments of the present application provide a pixel circuit and a display device, which eliminate the influence of a threshold voltage by compensating the threshold voltage of a driving transistor driving a light emitting element, thereby eliminating the phenomenon of non-uniform light emission of the display device. In order to achieve the above object, the embodiments of the present application provide the following technical solutions, which are specifically described in detail with reference to fig. 1 to 7.
Referring to fig. 1, a schematic structural diagram of a pixel circuit provided in an embodiment of the present disclosure is shown, where the pixel circuit is used to drive a light emitting element D, where the light emitting element D may be an organic light emitting diode. The pixel circuit includes: a first transistor M1, a second transistor M2, a third transistor M3, a fourth transistor M4, a fifth transistor M5, a driving transistor M0, a first capacitor C1 and a second capacitor C2;
the first transistor M1 is controlled by a first driving signal S1 for transmitting a driving current from the driving transistor M0 to the light emitting element D;
the second transistor M2 is controlled by a second driving signal S2 for controlling the electrical connection or insulation between the gate of the driving transistor M0 and the drain of the driving transistor M0;
the third transistor M3 is controlled by a third driving signal S3, and is used for transmitting a reset voltage Vref1 to the gate of the driving transistor M0, so as to drive the driving transistor M0 to be turned on;
the fourth transistor M4 is controlled by a fourth driving signal S4, and is used for transmitting a reference voltage Vref2 to the first plate of the first capacitor C1, and the second plate of the first capacitor C1 is electrically connected to the gate of the driving transistor M0;
the fifth transistor M5 is controlled by a fifth driving signal S5, and is used for transmitting a Data voltage Data to the first plate of the first capacitor C1;
the driving transistor M0 is used to determine the magnitude of the driving current, the source of the driving transistor M0 and the first plate of the second capacitor C2 are both connected to the power voltage Pvdd, and the second plate of the second capacitor C2 is electrically connected to the gate of the driving transistor M0.
Specifically, referring to fig. 1, in the pixel circuit provided in the embodiment of the present application, the gate of the first transistor M1 is connected to the first driving signal S1, the first electrode of the first transistor M1 is electrically connected to the drain of the driving transistor M0, and the second electrode of the first transistor M1 is electrically connected to the light emitting element D; wherein, the anode of the light emitting device D is electrically connected to the second electrode of the first transistor M1, and the cathode of the light emitting device D is connected to the cathode low potential Pvee;
the gate of the second transistor M2 is connected to the second driving signal S2, the first electrode of the second transistor M2 is electrically connected to the drain of the driving transistor M0, and the second electrode of the second transistor M2 is electrically connected to the gate of the driving transistor M0;
the gate of the third transistor M3 is connected to the third driving signal S3, the first electrode of the third transistor M3 is connected to the reset voltage Vref1, and the second electrode of the third transistor M3 is electrically connected to the gate of the driving transistor M0;
the gate of the fourth transistor M4 is connected to the fourth driving signal S4, the first electrode of the fourth transistor M4 is connected to the reference voltage Vref2, and the second electrode of the fourth transistor M4 is electrically connected to the first plate of the first capacitor C1;
the gate of the fifth transistor M5 is connected to the fifth driving signal S5, the first electrode of the fifth transistor M5 is connected to the Data voltage Data, and the second electrode of the fifth transistor M5 is electrically connected to the first plate of the first capacitor C1.
It should be noted that the conductivity type of each transistor provided in the present application is not particularly limited, and needs to be specifically selected according to the actual application. Optionally, in order to ensure a simple process of the pixel circuit, referring to fig. 1, the first transistor M1, the second transistor M2, the third transistor M3, the fourth transistor M4, the fifth transistor M5, and the driving transistor M0 provided in this embodiment of the present application are all P-type transistors.
In any of the above embodiments, the data voltage provided by the present application is greater than the reference voltage, and the reference voltage is not greater than the power supply voltage; the reference voltage is transmitted to the first pole plate of the first capacitor through the fourth transistor in the light-emitting stage, then the voltage difference generated by the reference voltage and the original voltage of the second node is coupled to the grid electrode of the driving transistor through the first capacitor, and because the data voltage is greater than the reference voltage and the reference voltage is not greater than the power voltage, the grid electrode voltage of the driving transistor is ensured to be less than the source electrode voltage of the driving transistor in the light-emitting stage, the normal conduction of the driving transistor is ensured, and the condition that a pixel circuit fails is avoided. In addition, referring to fig. 1, the reference voltage Vref2 provided by the embodiment of the present application may be smaller than the power supply voltage Pvdd, and the reference voltage Vref2 and the power supply voltage Pvdd are output by different voltage terminals; that is, by setting different voltage ends of the reference voltage Vref2 and the power supply voltage Pvdd to output, the data voltage is prevented from being too large, and the voltage application range of the driving IC of the display device is further adapted;
or,
referring to fig. 2, a schematic structural diagram of another pixel circuit provided in this embodiment of the present application is shown, where the reference voltage Vref2 may also be the same as the power supply voltage Pvdd, and the reference voltage Vref2 and the power supply voltage Pvdd are output from the same voltage end, that is, the first electrode of the fourth transistor M4 is electrically connected to the source of the driving transistor M0, so that fewer voltage ports of the pixel circuit are ensured, and the wiring difficulty is reduced.
Further, referring to fig. 2 and fig. 3, a driving process of the pixel circuit according to the embodiment of the present application will be described in detail, and fig. 3 is a timing diagram of a driving signal according to the embodiment of the present application. It should be noted that the following description takes the transistors as P-type transistors as an example. Referring to fig. 3, the driving method of the pixel circuit includes three stages, i.e., an initialization stage T1, a threshold voltage detection stage T2 and a light emitting stage T3, wherein a connection end between the gate of the driving transistor M0 and the second plate of the first capacitor C1 is defined as a first node N1, and a connection end between the first plate of the first capacitor C1 and the second electrode of the fourth transistor M4 is defined as a second node N2;
in the initialization period T1, the third driving signal S3 drives the third transistor M3 to be turned on, the fourth driving signal S4 drives the fourth transistor M4 to be turned off, and the fifth driving signal S5 drives the fifth transistor M5 to be turned on; in this stage, the voltage of the first node N1 is the reset voltage Vref1, the voltage of the second node N2 is the Data voltage Data, and the voltages of the first node N1 and the second node N2 are cooperatively maintained by the first capacitor C1 and the second capacitor C2;
during the threshold voltage detecting period T2, the first driving signal S1 drives the first transistor M1 to be turned off, the second driving signal S2 drives the second transistor M2 to be turned on, the third driving signal S3 drives the third transistor M3 to be turned off, the fourth driving signal S4 drives the fourth transistor M4 to be turned off, and the fifth driving signal S5 drives the fifth transistor M5 to be turned on; wherein the voltage of the first node N1 at this stage becomes the power supply voltage Pvdd minus the difference Pvdd-Vth of the threshold voltage Vth of the driving transistor M0, while the voltage of the second node N2 is maintained as the Data voltage Data;
in the light-emitting period T3, the first driving signal S1 drives the first transistor M1 to be turned on, the second driving signal S2 drives the second transistor M2 to be turned off, the third driving signal S3 drives the third transistor M3 to be turned off, the fourth driving signal S4 drives the fourth transistor M4 to be turned on, and the fifth driving signal S5 drives the fifth transistor M5 to be turned off. In this stage, the reference voltage Vref2(Pvdd) is transmitted to the second node N2 through the fourth transistor M4, generating a voltage difference V ═ Vref2-Data, and this voltage difference V' is coupled to the first node N1 through the combined action of the first capacitor C1 and the second capacitor C2, so that the voltage of the first node N1 (i.e., the gate voltage of the driving transistor M0) is Pvdd-Vth + (Pvdd-Data) [ C1/(C1+ C2)]Further derive the driving current I at this stageoled＝K*(Vsg-Vth)2＝K*{Pvdd-Pvdd+Vth-(Pvdd-Data)*[C1/(C1+C2)]-Vth}2＝K*(Data-Pvdd)*[C1/(C1+C2)]2Where k is a constant and Vsg is the source voltage (Pvdd) of the driving transistor M0 and its gate voltage { Pvdd-Vth + (Pvdd-Data) } [ C1/(C1+ C2)]The difference.
From the above, the driving current I generated by the driving transistor M0oledThat is, the drive current for driving the light emitting element D has a value independent of the threshold voltage of the drive transistor M0, and is passed through by the drive current IoledThe light emitting element D is driven, so that the light emission of the display device is uniform, and the display effect of the display device is improved.
In the initialization stage T1, the state of the second transistor M2 may be an on state or an off state. That is, with reference to fig. 2 and fig. 3, in the pixel circuit provided in the embodiment of the present application, the second transistor M2 is driven to be turned off by the second driving signal S2 during the initialization period T1, and the second driving signal S2 and the fifth driving signal S5 may not be the same, that is, output from different voltage ports; in addition, referring to fig. 4, a schematic structural diagram of another pixel circuit provided in the embodiment of the present application is shown, wherein the second transistor M2 is driven to be turned on by the second driving signal S2 during the initialization period T1, the second driving signal S2 is the same as the fifth driving signal S5, and the second driving signal S2 and the fifth driving signal S5 are output from the same driving signal terminal, that is, the gate of the second transistor M2 is electrically connected to the gate of the fifth transistor M5 and connected to a driving signal terminal.
Further, referring to fig. 2 and fig. 5, fig. 5 is another timing diagram of driving signals provided in the embodiment of the present application, and it should be noted that the following description takes the transistors as P-type transistors as an example.
The driving method of the pixel circuit comprises an initialization stage T1, a threshold voltage detection stage T2 and a light-emitting stage T3, wherein a connection end between the gate of the driving transistor M0 and the second plate of the first capacitor C1 is defined as a first node N1, and a connection end between the first plate of the first capacitor C1 and the second electrode of the fourth transistor M4 is defined as a second node N2;
in the initialization period T1, the third driving signal S3 drives the third transistor M3 to be turned on, the fourth driving signal S4 drives the fourth transistor M4 to be turned off, and the fifth driving signal S5 drives the fifth transistor M5 to be turned on; in this stage, the voltage of the first node N1 is the reset voltage Vref1, the voltage of the second node N2 is the Data voltage Data, and the voltages of the first node N1 and the second node N2 are cooperatively maintained by the first capacitor C1 and the second capacitor C2;
during the threshold voltage detecting period T2, the first driving signal S1 drives the first transistor M1 to be turned off, the second driving signal S2 drives the second transistor M2 to be turned on, the third driving signal S3 drives the third transistor M3 to be turned off, the fourth driving signal S4 drives the fourth transistor M4 to be turned off, and the fifth driving signal S5 drives the fifth transistor M5 to be turned on; wherein the voltage of the first node N1 at this stage becomes the power supply voltage Pvdd minus the difference Pvdd-Vth of the threshold voltage Vth of the driving transistor M0, while the voltage of the second node N2 is maintained as the Data voltage Data;
in the light-emitting period T3, the first driving signal S1 drives the first transistor M1 to be turned on, the second driving signal S2 drives the second transistor M2 to be turned off, the third driving signal S3 drives the third transistor M3 to be turned off, the fourth driving signal S4 drives the fourth transistor M4 to be turned on, and the fifth driving signal S5 drives the fifth transistor M5 to be turned off. In this stage, the reference voltage Vref2(Pvdd) is transmitted to the second node N2 through the fourth transistor M4, generating a voltage difference V ═ Vref2-Data, and this voltage difference V' is coupled to the first node N1 through the combined action of the first capacitor C1 and the second capacitor C2, so that the voltage of the first node N1 (i.e., the gate voltage of the driving transistor M0) is Pvdd-Vth + (Pvdd-Data) [ C1/(C1+ C2)]Further, the driving current Ioled at this stage is derived from K (Vsg-Vth)2＝K*{Pvdd-Pvdd+Vth-(Pvdd-Data)*[C1/(C1+C2)]-Vth}2＝K*(Data-Pvdd)*[C1/(C1+C2)]2Where K is a constant and Vsg is the source voltage (Pvdd) of the driving transistor M0 and its gate voltage { Pvdd-Vth + (Pvdd-Data) } [ C1/(C1+ C2)]The difference.
From the above, the driving current I generated by the driving transistor M0oledThat is, the drive current for driving the light emitting element D has a value independent of the threshold voltage of the drive transistor M0, and is passed through by the drive current IoledThe light emitting element D is driven, so that the light emission of the display device is uniform, and the display effect of the display device is improved.
Further, in the initialization period T1, the first transistor M1 may be driven to be turned on by the first driving signal S1 (or driven to be turned off by the first driving signal); in addition, referring to fig. 5, before the first driving signal S1 of the light emitting period T3 drives the first transistor M1 to be turned on, the light emitting period T3 further includes:
after the first driving signal S1 drives the first transistor M1 to turn off for a preset time period, the first driving signal S1 drives the first transistor M1 to turn on;
the states of the other transistors in the light-emitting period T3 are the same as those in the above embodiment, that is, the second driving signal S2 drives the second transistor M2 to turn off, the third driving signal S3 drives the third transistor M3 to turn off, the fourth driving signal S4 drives the fourth transistor M4 to turn on, and the fifth driving signal S5 drives the fifth transistor M5 to turn off.
With reference to the driving timing diagram shown in fig. 5, in the light-emitting period T3, the scheme that the first transistor M1 is turned on after being turned off first enables the first node N1 to stably write the Data voltage Data in the state that the first transistor M1 is turned off, so as to ensure that the Data voltage Data is written accurately, and then the light-emitting element D emits light after the first transistor M1 is turned on.
In the initialization period T1, the state of the first transistor M1 may be an on state or an off state. Referring to fig. 6, a schematic structural diagram of another pixel circuit provided in the embodiment of the present disclosure is shown, in the pixel circuit provided in the embodiment of the present disclosure, the first transistor M1 is driven to be turned off by the first driving signal S1 in the initialization period T1, the first driving signal S1 is the same as the fourth driving signal S4, and the first driving signal S1 and the fourth driving signal S4 are output from the same driving signal terminal, that is, the gate of the first transistor M1 and the gate of the fourth transistor M4 may be electrically connected and then connected to a driving signal terminal. In this case, the first transistor M1 is driven to turn off during the initialization period T1, so as to avoid the short-time lighting of the light emitting element D during the initialization period T1. In addition, on the basis of the pixel circuit shown in fig. 6, the gate of the second transistor M2 is connected to the gate of the fifth transistor M5, and referring to fig. 7, a structural schematic diagram of another pixel circuit provided in the embodiments of the present application is shown, wherein the gate of the second transistor M2 is connected to the gate of the fifth transistor M5, so that the number of ports is further reduced, and the difficulty in wiring the pixel circuit is reduced.
Correspondingly, an embodiment of the present application further provides a display device, where the display device includes the pixel circuit provided in any one of the above embodiments.
The embodiment of the application provides a pixel circuit and a display device, including: the driving circuit comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a driving transistor, a first capacitor and a second capacitor; through the matched driving between each transistor and the two capacitors, the driving current and the threshold voltage of the driving transistor are unrelated, the influence of adverse factors is eliminated, the problem of uneven light emission of the display device is effectively solved, and the light emission uniformity and the display effect of the display device are improved.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A pixel circuit for driving a light emitting element, comprising: the driving circuit comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a driving transistor, a first capacitor and a second capacitor;
the first transistor is controlled by a first driving signal for transmitting a driving current from the driving transistor to the light emitting element;
the second transistor is controlled by a second driving signal and is used for controlling the grid electrode of the driving transistor and the drain electrode of the driving transistor to be electrically connected or insulated;
the third transistor is controlled by a third driving signal and is used for transmitting a reset voltage to the grid electrode of the driving transistor so as to drive the driving transistor to be conducted;
the fourth transistor is controlled by a fourth driving signal and is used for transmitting a reference voltage to the first plate of the first capacitor, and the second plate of the first capacitor is electrically connected with the grid electrode of the driving transistor;
the fifth transistor is controlled by a fifth driving signal and is used for transmitting a data voltage to the first plate of the first capacitor;
the driving transistor is used for determining the magnitude of the driving current, the source electrode of the driving transistor and the first plate of the second capacitor are both connected with a power supply voltage, and the second plate of the second capacitor is electrically connected with the grid electrode of the driving transistor.
2. The pixel circuit according to claim 1, wherein a gate of the first transistor is connected to the first driving signal, a first electrode of the first transistor is electrically connected to a drain of the driving transistor, and a second electrode of the first transistor is electrically connected to the light-emitting element;
the grid electrode of the second transistor is connected with the second driving signal, the first electrode of the second transistor is electrically connected with the drain electrode of the driving transistor, and the second electrode of the second transistor is electrically connected with the grid electrode of the driving transistor;
the grid electrode of the third transistor is connected with the third driving signal, the first electrode of the third transistor is connected with the reset voltage, and the second electrode of the third transistor is electrically connected with the grid electrode of the driving transistor;
a grid electrode of the fourth transistor is connected with the fourth driving signal, a first electrode of the fourth transistor is connected with the reference voltage, and a second electrode of the fourth transistor is electrically connected with a first polar plate of the first capacitor;
the grid electrode of the fifth transistor is connected with the fifth driving signal, the first electrode of the fifth transistor is connected with the data voltage, and the second electrode of the fifth transistor is electrically connected with the first polar plate of the first capacitor.
3. The pixel circuit of claim 1, wherein the data voltage is greater than the reference voltage, and wherein the reference voltage is not greater than the supply voltage.
4. The pixel circuit according to claim 3, wherein the reference voltage and the power supply voltage are the same, and the reference voltage and the power supply voltage are output from the same voltage terminal;
or, the reference voltage is smaller than the power supply voltage, and the reference voltage and the power supply voltage are output by different voltage ends.
5. The pixel circuit according to claim 1, wherein the driving method of the pixel circuit comprises three phases of an initialization phase, a threshold voltage detection phase and a light emitting phase, wherein,
in the initialization stage, the third driving signal drives the third transistor to be turned on, the fourth driving signal drives the fourth transistor to be turned off, and the fifth driving signal drives the fifth transistor to be turned on;
in the threshold voltage detection stage, the first driving signal drives the first transistor to be turned off, the second driving signal drives the second transistor to be turned on, the third driving signal drives the third transistor to be turned off, the fourth driving signal drives the fourth transistor to be turned off, and the fifth driving signal drives the fifth transistor to be turned on;
in the light emitting stage, the first driving signal drives the first transistor to be turned on, the second driving signal drives the second transistor to be turned off, the third driving signal drives the third transistor to be turned off, the fourth driving signal drives the fourth transistor to be turned on, and the fifth driving signal drives the fifth transistor to be turned off.
6. The pixel circuit according to claim 5, wherein the second driving signal and the fifth driving signal are the same, and the second driving signal and the fifth driving signal are output from the same driving signal terminal.
7. The pixel circuit according to claim 5, wherein the first drive signal and the fourth drive signal are the same, and the first drive signal and the fourth drive signal are output from the same drive signal terminal.
8. The pixel circuit according to claim 5, wherein before the first driving signal in the light-emitting phase drives the first transistor to be turned on, the light-emitting phase further comprises:
after the first driving signal drives the first transistor to be turned off for a preset time period, the first driving signal drives the first transistor to be turned on;
the second driving signal drives the second transistor to be turned off, the third driving signal drives the third transistor to be turned off, the fourth driving signal drives the fourth transistor to be turned on, and the fifth driving signal drives the fifth transistor to be turned off.
9. The pixel circuit according to claim 1, wherein the first transistor, the second transistor, the third transistor, the fourth transistor, the fifth transistor, and the driving transistor are all P-type transistors.
10. A display device comprising the pixel circuit according to any one of claims 1 to 9.
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| CN201610077714.1A CN105489166A (en) | 2016-02-03 | 2016-02-03 | Pixel circuit and display device |
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| CN201610077714.1A CN105489166A (en) | 2016-02-03 | 2016-02-03 | Pixel circuit and display device |
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Application publication date: 20160413 |