CN114220382A - Pixel driving circuit, display panel and display device - Google Patents
Pixel driving circuit, display panel and display device Download PDFInfo
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- CN114220382A CN114220382A CN202111504572.XA CN202111504572A CN114220382A CN 114220382 A CN114220382 A CN 114220382A CN 202111504572 A CN202111504572 A CN 202111504572A CN 114220382 A CN114220382 A CN 114220382A
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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
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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
- G09G2310/00—Command of the display device
- G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
- G09G2310/0264—Details of driving circuits
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Abstract
The application provides a pixel driving circuit, a display panel and a display device, and relates to the technical field of display; the pixel driving circuit comprises a driving transistor, a light-emitting element and at least one switching transistor module; the driving transistor is used for driving the light-emitting element, and the grid electrode of the driving transistor is connected to the first node; the switch transistor module comprises a first transistor and a second transistor, wherein the first pole of the first transistor is connected with the first node, and the second pole of the first transistor is connected with the first pole of the second transistor; the leakage current of the second transistor is larger than that of the first transistor; when the first transistor and the second transistor are in the off state, the second transistor leaks electricity to the outer side far away from the first node, so that the potential change of the first node is reduced or even eliminated, the driving current received by the light-emitting element in the light-emitting state is in a stable state, and the problem of continuous flicker of a picture is favorably improved or eliminated.
Description
Technical Field
The present invention relates to the field of display technologies, and in particular, to a pixel driving circuit, a display panel, and a display device.
Background
Nowadays, as the information society develops, the demand for displays for representing information is also increasing. Accordingly, the demand of users for small, light and effective flat panel displays is increasing.
As personal devices are more prevalent, portable and/or wearable devices are being actively developed, which are required to have a feature of low power consumption in order to apply the display device to the portable and/or wearable devices; however, with the techniques developed so far, there is a limit to obtaining a display having excellent low power consumption performance. For example, in the prior art, under the condition of low-frequency display of a display product, the waveform brightness of a pixel falls downward within one frame, which causes the problem of flickering of a display screen and affects the experience effect of a user. Therefore, it is desirable to provide a method for improving the flicker problem of the display device.
Disclosure of Invention
In view of the above, the present invention provides a pixel driving circuit, a display panel and a display device to improve the problem of flicker of a display product.
In a first aspect, the present application provides a pixel driving circuit, comprising:
a driving transistor, a light emitting element and at least one switching transistor module;
the driving transistor is used for driving the light-emitting element, and the grid electrode of the driving transistor is connected to a first node;
the switch transistor module comprises a first transistor and a second transistor, wherein a first pole of the first transistor is connected to the first node, and a second pole of the first transistor is connected to a first pole of the second transistor;
the leakage current of the second transistor is greater than the leakage current of the first transistor.
In a second aspect, the present application provides a display panel comprising the pixel driving circuit.
In a third aspect, the present application provides a display device comprising the display panel.
Compared with the prior art, the pixel driving circuit, the display panel and the display device provided by the invention at least realize the following beneficial effects:
the application provides a pixel driving circuit, a display panel and a display device, wherein a switch transistor module arranged in the pixel driving circuit comprises a first transistor and a second transistor which are connected in series, wherein the second transistor is far away from a first node compared with the first transistor, through adjustment of the second transistor, the leakage current of the second transistor is larger than that of the first transistor in the working process of the pixel driving circuit, so that when the first transistor and the second transistor are in a closed state, the leakage current leaks to the outer side far away from the first node through the second transistor, thereby reducing or even eliminating the potential change of the first node in the whole process that a light-emitting element is in a light-emitting state, so that the driving current received by the light-emitting element in the light-emitting state is in a stable state, and the light-emitting element is beneficial to keeping a stable light-emitting brightness in the light-emitting state, the problem of continuous flicker of the picture is improved or eliminated.
Of course, it is not necessary for any product in which the present invention is practiced to achieve all of the above-described technical effects simultaneously.
Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.
Fig. 1 is a circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 2 is a circuit diagram of another pixel driving circuit according to an embodiment of the present disclosure;
fig. 3 is a circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 4 is a graph comparing current-voltage curves of a first transistor and a second transistor provided in an embodiment of the present application;
fig. 5 is a driving timing diagram of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 6 is a diagram illustrating a structure of a film layer of a first transistor and a second transistor according to an embodiment of the present disclosure;
fig. 7 is a diagram illustrating another structure of a film layer of a first transistor and a second transistor according to an embodiment of the present disclosure;
fig. 8 is a diagram illustrating a structure of another film layer of the first transistor and the second transistor according to the embodiment of the present application;
fig. 9 is a schematic view of a display panel according to an embodiment of the present disclosure;
fig. 10 is a schematic view of a display device according to an embodiment of the present disclosure.
Detailed Description
Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.
The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.
Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.
In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
In the prior art, under the condition of displaying a low-frequency display product, the waveform brightness of a pixel falls downwards within a frame, so that a display picture has a problem of flickering lamps, and the experience effect of a user is influenced. Therefore, it is desirable to provide a method for improving the flicker problem of the display device.
The present invention provides a pixel driving circuit, a display panel and a display device to improve the problem of flicker of the display product.
Fig. 1 is a circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure, fig. 2 is another circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure, fig. 3 is another circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure, and referring to fig. 1 to fig. 3, the present disclosure provides a pixel driving circuit 100, including:
a driving transistor M3, a light emitting element D1, and at least one switching transistor module 10;
the driving transistor M3 is used for driving the light emitting element D1, and the gate of the driving transistor M3 is connected to the first node N1;
the switch transistor module 10 comprises a first transistor M4-1/M5-1 and a second transistor M4-2/M5-2, wherein a first pole of the first transistor M4-1/M5-1 is connected to a first node N1, and a second pole of the first transistor M4-1/M5-1 is connected to a first pole of the second transistor M4-2/M5-2;
the leakage current of the second transistor M4-2/M5-2 is greater than that of the first transistor M4-1/M5-1.
Specifically, the present application provides a pixel driving circuit 100 with a novel structural design, the pixel driving circuit 100 includes a driving transistor M3, a light emitting element D1, and at least one switching transistor module 10; the gate of the driving transistor M3 is connected to the first node N1 of the pixel driving circuit 100.
The switch transistor module 10 provided in the present application comprises two transistor units, namely a first transistor M4-1/M5-1 and a second transistor M4-2/M5-2, where a first pole of the first transistor M4-1/M5-1 is connected to a first node N1 in the pixel driving circuit 100, and a second pole of the first transistor M4-1/M5-1 is connected to a first pole of the second transistor M4-2/M5-2; that is, the first transistor M4-1/M5-1 and the second transistor M4-2/M5-2 are connected in series.
When the light emitting element in the pixel driving circuit is in a light emitting state, the switching transistor module is in an off state, for example, the first transistor and the second transistor are both in an off state.
If the first transistor and the second transistor have the same arrangement structure, the same leakage condition and a serious leakage condition, the leakage current of the first transistor causes the potential of the first node in the pixel driving circuit to change greatly in the whole process that the light-emitting element is in a light-emitting state; since the potential of the first node may affect the magnitude of the driving current of the driving transistor, and further affect the luminance of the light emitting device, the transistors connected in series with the same leakage degree may cause the image to flicker continuously when the light emitting device is in the light emitting state.
In order to solve the problem of image flicker, the leakage current of the second transistor M4-2/M5-2 in the switch transistor module 10 is set to be larger than the leakage current of the first transistor M4-1/M5-1, so that the first transistor M4-1/M5-1 and the second transistor M4-2/M5-2 leak current to the outside (Vref or N3 side) far away from the first node N1 through the second transistor M4-2/M5-2 when in the off state, thereby reducing or even eliminating the potential change of the first node N1 in the whole process that the light emitting element D1 is in the light emitting state, so that the driving current received by the light emitting element D1 in the light emitting state is in a stable state, which is beneficial for the light emitting element D1 to maintain a stable light emitting brightness in the light emitting state, the problem of continuous flicker of the picture is improved or eliminated.
It should be noted that, in this embodiment, the transistor may be a thin film transistor, and in the first electrode and the second electrode of the transistor in this embodiment, one of the first electrode and the second electrode is a source electrode of the transistor, and the other is a drain electrode of the transistor.
It should be added that fig. 1, fig. 2, and fig. 3 show three circuit structure designs of the pixel driving circuit 100, which all belong to the protection scope of the present application, and specific differences in the circuit structures of fig. 1, fig. 2, and fig. 3 will be described in detail later.
With reference to fig. 1-3, alternatively, the gates of the first transistor M4-1/M5-1 and the second transistor M4-2/M5-2 are electrically connected to the same circuit control terminal S1/S2.
Specifically, the gates of the first transistor M4-1/M5-1 and the second transistor M4-2/M5-2 in the switch transistor module 10 are electrically connected to the same circuit control terminal S1/S2.
Taking the first transistor M4-1/M5-1 and the second transistor M4-2/M5-2 as an example, if the first transistor M4-1/M5-1 and the second transistor M4-2/M5-2 are both P-type transistors, the circuit control terminal S1/S2 is required to transmit an electrical signal to the gates of the first transistor M4-1/M5-1 and the second transistor M4-2/M5-2, and at this time, the electrical signal transmitted by the circuit control terminal S1/S2 has a process of jumping, specifically, from a low level to a high level, and the first transistor M4-1/M5-1 and the second transistor M4-2/M5-2 are both driven to be in a turned-off state by a high level signal. At this time, due to the capacitive coupling, the potentials of the serial positions (the fifth node N5 and/or the sixth node N6) of the first transistor M4-1/M5-1 and the second transistor M4-2/M5-2 are increased, and a relatively large voltage difference exists between the fifth node N5 and/or the sixth node N6 and the first node N1, and the larger the voltage difference between the two ends of the first transistor M4-1/M5-1 is, the more serious the leakage phenomenon is caused.
For the above reasons, the present application sets the leakage current of the second transistor M4-2/M5-2 in the switch transistor module 10 to be larger than the leakage current of the first transistor M4-1/M5-1, so that the first transistor M4-1/M5-1 and the second transistor M4-2/M5-2 are in the off state, and the leakage current is leaked to the outside (Vref or N3 side) far away from the first node N1 through the second transistor M4-2/M5-2, so as to achieve the purpose of rapidly reducing the potential rise of the fifth node N5 and/or the sixth node N6, thereby reducing or even eliminating the voltage difference between the fifth node N5 and/or the sixth node N6 and the first node N1, and further reducing or even eliminating the potential change of the first node N1 during the whole process of the light emitting state of the light emitting element D1, therefore, the driving current received by the light emitting element D1 in the light emitting state is in a stable state, which is beneficial to maintaining a stable light emitting brightness of the light emitting element D1 in the light emitting state, and improving or eliminating the problem of continuous flicker of the picture.
As shown in fig. 2 and 3, the switching transistor module 10 optionally includes a first switching transistor module 11, and the first switching transistor module 11 is configured to transmit the reference voltage to the first node N1.
In the pixel driving circuit 100 provided by the present application, the switching transistor module 10 in the pixel driving circuit 100 includes a first switching transistor module 11, one end of the first switching transistor module 11 is electrically connected to the first node N1, and the other end of the first switching transistor module 11 is electrically connected to the reference voltage terminal Vref1, the first switching transistor module 11 is configured to transmit the reference voltage provided by the reference voltage terminal Vref1 to the first node N1, and is configured to reset the gate of the driving transistor M3.
Specifically, the first switch transistor module 11 includes a first transistor M5-1 and a second transistor M5-2, a first pole of the first transistor M5-1 is connected to the first node N1, a second pole of the first transistor M5-1 and a first pole of the second transistor M5-2 are both connected to the fifth node N5, and a second pole of the second transistor M5-2 is connected to the reference voltage terminal Vref 1. Wherein, when the first switch transistor module 11 is in the off state (i.e. the first transistor M5-1 and the second transistor M5-2 are both in the off state), the leakage current of the second transistor M5-2 is greater than the leakage current of the first transistor M5-1 (wherein, the first transistor M5-1 may hardly generate the leakage current condition), so the potential-boosted fifth node N5 is mainly leaked to the reference voltage terminal Vref1, and thus, the leakage current of the second transistor M5-2 to the reference voltage terminal Vref1 is used to quickly adjust the potential of the fifth node N5, for example, the potential of the fifth node N5 is quickly lowered, thereby reducing the voltage difference between the fifth node N5 and the first node N1, reducing or eliminating the influence on the potential of the first node N1, and when the light emitting element D1 is in the light emitting stage, the potential of the first node N1 may be kept stable, the driving current of the driving transistor M3 driving the light emitting device D1 can be kept stable, i.e., the luminance of the light emitting device D1 does not change, which is beneficial to improving or eliminating the problem of image flicker.
As shown in fig. 1 and 3, optionally, the switching transistor module 10 includes a second switching transistor module 12, and the second switching transistor module 12 is connected between the gate of the driving transistor M3 and the second pole of the driving transistor M3.
The switching transistor module 10 in the pixel driving circuit 100 includes a second switching transistor module 12, one end of the second switching transistor 12 is electrically connected to the first node N1, and the other end is electrically connected to the third node N3, that is, the second switching transistor module 12 is electrically connected between the gate of the driving transistor M3 and the second pole of the driving transistor M3, and the second switching transistor module 12 is used for compensating the threshold voltage of the driving transistor M3.
Specifically, the second switching transistor module 12 includes a first transistor M4-1 and a second transistor M4-2, a first pole of the first transistor M4-1 is connected to the first node N1, a second pole of the first transistor M4-1 and a first pole of the second transistor M4-2 are both connected to the sixth node N6, and a second pole of the second transistor M4-2 is connected to the third node N3. Wherein, when the second switching transistor module 12 is in the off state (i.e. the first transistor M4-1 and the second transistor M4-2 are both in the off state), the leakage current of the second transistor M4-2 is greater than the leakage current of the first transistor M4-1, so the potential-raised sixth node N6 mainly leaks to the third node N3, thereby the leakage current to the third node N3 through the second transistor M4-2 rapidly adjusts the potential of the sixth node N6, for example, rapidly lowers the potential of the sixth node N6, thereby reducing the voltage difference between the sixth node N6 and the first node N1, reducing or eliminating the influence on the potential of the first node N1, when the light emitting element D1 is in the light emitting stage, the potential of the first node N1 can be kept stable, the driving current of the driving light emitting element D1 of the driving transistor M3 can be kept stable, that is, the brightness of the light emitting element D1 is not changed, which is beneficial to improving or eliminating the problem of image flicker.
Fig. 4 is a graph comparing current-voltage curves of a first transistor and a second transistor provided in an embodiment of the present application, wherein the abscissa represents the voltage difference between the control electrode (gate) and the source electrode of the transistors, and the ordinate represents the current value flowing through the transistors, please refer to fig. 1-4; it should be noted that the class B device shown in fig. 4 may be, for example, the second transistor M4-2 and/or the second transistor M5-2 in the pixel driving circuit provided in this application, and the remaining transistors in the pixel driving circuit provided in this application are all class a devices. The upper part of fig. 4 shows a current-voltage curve of the transistor as a class a device, and the lower part shows a current-voltage curve of the transistor as a class B device.
Alternatively, referring to the lower diagram of fig. 4, the second transistor M4-2/M5-2 has a first current-voltage characteristic when the voltage difference between the first electrode and the control electrode is a first voltage difference, and has a second current-voltage characteristic when the voltage difference between the first electrode and the control electrode is a second voltage difference;
wherein the second pressure differential is greater than the first pressure differential.
Specifically, in the pixel driving circuit provided by the application, the second transistor M4-2 and/or the second transistor M5-2 are/is a class B transistor, and the current-voltage curve of the normal transistor (such as a class a transistor) is substantially the same when the second transistor M4-2/M5-2 is in an on state, that is, the on state of the normal transistor is shown and the normal transistor operates as the normal transistor; when the second transistor M4-2/M5-2 is in an off state, that is, corresponding to a second voltage difference in the voltage difference between the control electrode (gate) and the source thereof, it exhibits another current-voltage characteristic (second current-voltage characteristic) different from that of a normal transistor. Specifically, the second transistor exhibits a DIBL (Drain Induced Barrier Lowering) effect when in an off state.
It should be noted that, as shown in fig. 4, when the voltage difference between the gate and the source of the second transistor M4-2/M5-2 is smaller than about 2V (-between 5V and close to the 5V side), for example, in the left region along the longitudinal chain line, the voltage difference between the gate and the source of the second transistor M4-2/M5-2 is a first voltage difference, and exhibits a first current-voltage characteristic, that is, the same current-voltage characteristic as that of the transistor in the class a device; for example, when the voltage difference between the gate and the source of the second transistor M4-2/M5-2 is greater than about 2V, the voltage difference between the gate and the source of the second transistor M4-2/M5-2 is a second voltage difference, and a second current-voltage characteristic, i.e., a current-voltage characteristic different from that of the transistor in the class a device, is exhibited.
That is, the second transistor is a class B transistor, and when the second transistor is in an on state, the second transistor operates as a normal transistor; when it is in the off state, it takes advantage of the DIBL effect it exhibits to achieve regulation of the fifth node N5 and/or the sixth node N6.
It is also necessary to supplement that in the prior art, the DIBL effect exhibited by the transistor is a problem that the transistor needs to avoid, because the transistor exhibits the DIBL effect, which deteriorates the characteristics of the transistor. However, the present application overcomes the technical prejudice of those skilled in the art, and achieves the effect of rapidly decreasing the potential rise of the fifth node N5/the sixth node N6 by utilizing the DIBL effect exhibited by the transistor in the off state.
Specifically, referring to the upper part of fig. 4, for a normal transistor of a class a device, after the voltage difference between the control electrode (gate) and the source of the transistor is greater than about 2V, the value of the current flowing through the transistor is a very small value, so that the transistor is in an off state.
Therefore, for a normal class a transistor, the transistor should be in an off state after the voltage difference between the gate and the source of the transistor is greater than 2V.
In the switching transistor module 10 provided by the present application, the second transistor M4-2/M5-2 is a class B device, and as shown in the lower half of fig. 4, when a voltage difference between a gate (control electrode) and a source (first electrode) of the second transistor M4-2/M5-2 is, for example, less than about 6V (between 5V and 15V, on the side close to 5V), a current flowing across the source and the drain of the second transistor tends to gradually decrease; on the basis, however, when the voltage difference between the gate and the source of the second transistor M4-2/M5-2 is, for example, less than about 5V, the current flowing through the second transistor M4-2/M5-2 is always in a higher value range, and the current still flows between the source and the drain of the second transistor M4-2/M5-2, namely, when the voltage difference between the gate and the source of the transistor is, for example, greater than about 2V and less than about 5V, it still shows that the second transistor M4-2/M5-2 has a leakage condition, and the transistor is not in an off state.
When the voltage difference between the gate and the source of the second transistor M4-2/M5-2 is greater than about 6V, for example, the current flowing through the second transistor is only floated within a very small range of values, and the transistor can be turned off. That is, when the voltage difference between the gate and the source of the second transistor M4-2/M5-2 is, for example, greater than about 6V, the transistor can be in the off state.
Referring to fig. 1 and fig. 2, it should be noted that the first switching transistor module 11 is specifically a first reset module 11 in the pixel driving circuit 100 provided in the present application, and the second switching transistor module 12 is specifically a compensation module 12 in the pixel driving circuit 100 provided in the present application. It should be further noted that the present application provides an alternative embodiment that, as shown in fig. 1, only the first reset module 11 in the pixel driving circuit 100 uses the switching transistor module 10 provided in the present application; an alternative embodiment is also provided, as shown in fig. 2, in which only the compensation module 12 in the pixel driving circuit 100 uses the switching transistor module 10 provided in the present application; in addition, the present application also provides an alternative embodiment that, as shown in fig. 3, the first reset module 11 and the compensation module 12 in the pixel driving circuit 100 both use the switching transistor module 10 provided in the present application.
Fig. 5 is a driving timing diagram of a pixel driving circuit according to an embodiment of the present application, taking the transistors in the pixel driving circuit as P-type transistors as an example, please refer to fig. 3 and 5, for the following description, taking the example that the first reset module 11 and the compensation module 12 in the pixel driving circuit 100 provided by the present application both use the switching transistor module 10 provided by the present application, the gate of the driving transistor M3 in the pixel driving circuit 100 is connected to the first node N1, the first pole of the driving transistor M3 is connected to the second node N2, and the second pole of the driving transistor M3 is connected to the third node N3; an anode of the light emitting element D1 is connected to the fourth node N4, and a cathode thereof is electrically connected to the second power signal terminal PVEE; the first light emission control module 20 (including the transistor M1), the driving transistor M3, and the light emitting element D1 are connected in series between the first power signal terminal PVDD and the second power signal terminal PVEE; a first terminal of the storage module Cst (including the first capacitor C1) is electrically connected to the first power signal terminal PVDD, and a second terminal thereof is electrically connected to the first node N1; the gates of the first transistor M5-1 and the second transistor M5-2 in the first switch transistor module 11 are electrically connected to the first circuit control terminal S1, and the gates of the first transistor M4-1 and the second transistor M4-2 in the second switch cell transistor module 12 are electrically connected to the second circuit control terminal S2; a first pole of the transistor M2 is connected to the data signal terminal Vdata, a second pole is connected to the second node N2, and the control electrode is electrically connected to the second circuit control terminal S2; the second light-emitting control module 21 further includes a sixth transistor M6, a control electrode of the sixth transistor M6 is electrically connected to the light-emitting control signal terminal Emit, a first electrode is connected to the third node N3, and a second electrode is electrically connected to the light-emitting element D1; the second reset module 70 is further included, and the second reset module 70 includes a seventh transistor M7, a control terminal of the seventh transistor M7 is electrically connected to the third circuit control terminal S3, a first terminal of the seventh transistor M7 is electrically connected to a reference voltage terminal Vref2, and a second terminal of the seventh transistor M7 is electrically connected to the fourth node N4.
In the initialization stage T1, the first circuit control terminal S1 provides a low level, the first switch transistor module 11 is turned on, and the reference voltage terminal Vref1 transmits a reference voltage signal to the first node N1 through the first switch transistor module 11, so that the gate potential of the driving transistor M3 is reset.
In the data writing phase T2, the first circuit control terminal S1 provides a high level, the first switching transistor module 11 is turned off, the second circuit control terminal S2 provides a low level, the transistor M2 is turned on, the second switching transistor module 12 is turned on, the first node N1 is connected to the third node N3, the signal of the data signal terminal Vdata is transmitted to the second node N2, the signal of the second node N2 is transmitted to the third node N3 through the driving transistor M3, and the signal of the third node N3 is transmitted to the first node N1; the charging of the first node N1 and the maintenance of the voltage of the first node N1 are achieved by the storage module Cst.
In the lighting period T3, the first circuit control terminal S1 and the second circuit control terminal S2 both provide a high level, the first switching transistor module 11 and the second switching transistor module 12 are both in an off state, the first node N1 and the third node N3 are off, the first lighting control module 20 is turned on, the signal of the first power signal terminal PVDD is transmitted to the second node N2, the driving transistor M3 generates a driving current for driving the light emitting element D1 to emit light, and the driving current is transmitted to the light emitting element D1 through the second lighting control module 21, so that the light emitting element D1 emits light.
In the present application, the drain current of the second transistor M5-2/M4-2 in the first switch transistor module 11 and/or the second switch transistor module 12 is set to be larger than the drain current of the first transistor M5-1/M4-1 (wherein, the drain current of the first transistor M5-1/M4-1 may be smaller or no drain current), in the lighting period T3, so that when the first switch transistor module 11, the second switch transistor module 12 are in the off state, the potential of the fifth node N5 and/or the sixth node N6 is rapidly reduced to a potential close to the first node N1, so that the potential of the first node N1 hardly changes at the stage between the frame start and the frame end of the display panel frame display period, so that the driving current of the first node N1 is in a stable state during the lighting period T3 of the light emitting element D1, the light-emitting element D1 can keep a stable light-emitting brightness in the light-emitting state, and the problem of continuous flicker of the picture can be improved or eliminated.
It should be added that, in the pixel driving circuit 100 provided in the present application, all the transistors included are P-type transistors, but the present application is not limited thereto, and a user may also adjust at least a part of the transistors to be N-type transistors according to the requirement as long as the problem of image flicker can be improved. The P-type transistor is generally turned on by a low-level signal and turned off by a high-level signal, and the N-type transistor is generally turned on by a high-level signal and turned off by a low-level signal.
Fig. 6 is a film structure diagram of a first transistor and a second transistor according to an embodiment of the disclosure, please refer to fig. 6 in combination with fig. 1 to 3, alternatively, the first transistor M4-1/M5-1 includes a first active layer 51, a first gate insulating layer 52, and a first gate 53 sequentially disposed;
the second transistor M4-2/M5-2 includes a second active layer 61, a second gate insulating layer 62, and a second gate electrode 63, which are sequentially disposed;
the density of interface defect states 66 on the side of the second gate insulating layer 62 facing the second gate 63 is greater than the density of interface defect states 66 on the side of the first gate insulating layer 52 facing the first gate 53.
Specifically, in order to realize that the leakage current of the second transistor M4-2/M5-2 is greater than the leakage current of the first transistor M4-1/M5-1 in the switching transistor module 10, the present application provides a method for manufacturing the first transistor M4-1/M5-1 and the second transistor M4-2/M5-2 in such a manner that the first transistor M4-1/M5-1 includes a first active layer 51, a first gate insulating layer 52 and a first gate 53, which are sequentially disposed, the second transistor M4-2/M5-2 includes a second active layer 61, a second gate insulating layer 62 and a second gate 63, which are sequentially disposed, and the arrangement structure of the second transistor M4-2/M5-2 is different from that of the first transistor M4-1/M5-1, the side of the second gate insulating layer 62 facing the second gate 63 in the second transistor M4-2/M5-2 is set to a significant interface defect state 66, or the density of interface defect states 66 on the side of the second gate insulating layer 62 facing the second gate 63 is greater than the density of interface defect states 66 on the side of the first gate insulating layer 52 facing the first gate 53.
The interface defect state 66 can be achieved by performing plasma gas cleaning (plasma) on the film layer with gas such as oxygen or hydrogen, controlling different gas flow rates to form a thin defect layer on the surface of the film layer, and the like; as incorporated herein, the plasma gas cleaning is performed on the surface of the second gate insulating layer 66 facing the second gate 63, so that the interface defect state 66 with a relatively high density is formed on the surface of the second gate insulating layer 62 facing the second gate 63.
The first transistor M4-1/M5-1 device behaves normally by setting the side of the first gate insulating layer 52 facing the first gate 53 to have a smaller density of interface defect states 66; by setting the side of the second gate insulating layer 62 facing the second gate 63 to have a higher density of the interface defect state 66, specifically, a thin interface defect molecular layer with a higher density is arranged between the second gate insulating layer 62 and the second gate 63, so that the controllability of the second gate 63 is poorer, the device of the second transistor M4-2/M5-2 exhibits a DIBL (Drain induced barrier Lowering) effect, so that the leakage current of the second transistor M4-2/M5-2 is greater than that of the first transistor M4-1/M5-1 when the circuit is operated, and the potential of the fifth node N5 and/or the sixth node N6 is rapidly reduced.
Fig. 7 is another film structure diagram of the first transistor and the second transistor according to an embodiment of the disclosure, please refer to fig. 7 in combination with fig. 1 to 3, and optionally, the first transistor M4-1/M5-1 includes a first light shielding layer 54, a first insulating layer 55, a first active layer 51, a first gate insulating layer 52, and a first gate 53, which are sequentially disposed;
the second transistor M4-2/M5-2 includes a second light shielding layer 64, a second insulating layer 65, a second active layer 61, a second gate insulating layer 62, and a second gate electrode 63, which are sequentially disposed;
the first light shielding layer 54 is electrically connected to the first gate 53 (the electrical connection is shown by the perforation 56 in fig. 7), and the second light shielding layer 64 is electrically floating.
Specifically, in order to realize that the leakage current of the second transistor M4-2/M5-2 is greater than the leakage current of the first transistor M4-1/M5-1 in the switching transistor module 10, the present application provides a first transistor M4-1/M5-1 and a second transistor M4-2/M5-2 fabricated in such a manner that the first transistor M4-1/M5-1 includes a first light shielding layer 54, a first insulating layer 55, a first active layer 51, a first gate insulating layer 52 and a first gate 53, which are sequentially disposed, and the second transistor M4-2/M5-2 includes a second light shielding layer 64, a second insulating layer 65, a second active layer 61, a second gate insulating layer 62 and a second gate 63, which are sequentially disposed; the second transistor M4-2/M5-2 and the first transistor M4-1/M5-1 are different in arrangement in that the potential of the second light shielding layer 64 is set floating, and the first light shielding layer 54 is electrically connected to the first gate electrode 53.
By providing the floating second light shielding layer 64 on the side of the second gate insulating layer 62 facing the second gate 63, compared to the first transistor M4-1/M5-1, the second gate 63 of the second transistor M4-2/M5-2 is not electrically connected to the second light shielding layer 64, so that the control capability of the second gate 63 is poor, and the component of the second transistor M4-2/M5-2 exhibits the DIBL effect, so that the leakage current of the second transistor M4-2/M5-2 is greater than the leakage current of the first transistor M4-1/M5-1 during operation in the circuit, and the potential of the fifth node N5 and/or the sixth node N6 is rapidly reduced.
Fig. 8 is a diagram illustrating another film layer structure of the first transistor and the second transistor according to an embodiment of the present application, please refer to fig. 8 in combination with fig. 1-3, and optionally, the channel length L2 of the second transistor M4-2/M5-2 is smaller than the channel length L1 of the first transistor M4-1/M5-1.
Specifically, in order to realize that the leakage current of the second transistor M4-2/M5-2 is greater than the leakage current of the first transistor M4-1/M5-1 in the switching transistor module 10, the present application provides a manufacturing manner of the first transistor M4-1/M5-1 and the second transistor M4-2/M5-2, in which the first transistor M4-1/M5-1 includes a first active layer 51, a first gate insulating layer 52 and a first gate 53, which are sequentially disposed; the second transistor M4-2/M5-2 includes a second active layer 61, a second gate insulating layer 62, and a second gate electrode 63, which are sequentially disposed.
The channel length L2 of the second transistor M4-2/M5-2 is smaller than the channel length L1 of the first transistor M4-1/M5-1, specifically, the channel length L1 of the first transistor M4-1/M5-1 can be set to be more than 3 μ M, and the channel length L2 of the second transistor M4-2/M5-2 can be set to be less than 1.5 μ M; since the second transistor M4-2/M5-2 is configured such that the channel size is smaller than that of the first transistor M4-1/M5-1, resulting in poor controllability of the second gate 63, the component of the second transistor M4-2/M5-2 exhibits a DIBL effect, so that the leakage current of the second transistor M4-2/M5-2 is greater than that of the first transistor M4-1/M5-1 during operation in the circuit, and the potential of the fifth node N5 and/or the potential of the sixth node N6 are rapidly decreased.
Fig. 9 is a schematic diagram of a display panel according to an embodiment of the present application, please refer to fig. 9 in conjunction with fig. 1 to 8, and based on the same inventive concept, the present application further provides a display panel 200, where the display panel 200 includes a plurality of pixel units 99 arranged in a matrix, each of the pixel units 99 includes the aforementioned pixel driving circuit 100, and the pixel driving circuit 100 is any one of the pixel driving circuits 100 provided in the present application; the pixel driving circuit 100 is configured to cause the electrically connected light emitting element D1 to emit light, so that each pixel unit 99 in the display panel 200 performs display, thereby forming a display screen.
Fig. 10 is a schematic diagram of a display device according to an embodiment of the present application, please refer to fig. 10 in conjunction with fig. 1 to 9, and based on the same inventive concept, the present application further provides a display device 300, where the display device 300 includes a display panel 200, and the display panel 200 is any one of the display panels 200 provided in the present application.
It should be noted that, for the embodiments of the display device 300 provided in the embodiments of the present application, reference may be made to the embodiments of the display panel 200, and repeated descriptions are omitted. The display device 300 provided by the present application may be: any product and component with a display function, such as a mobile phone, a tablet computer, a television, a display, a notebook computer, a navigator and the like.
As can be seen from the foregoing embodiments, the pixel driving circuit, the display panel and the display device provided in the present invention at least achieve the following advantages:
the application provides a pixel driving circuit, a display panel and a display device, wherein a switch transistor module arranged in the pixel driving circuit comprises a first transistor and a second transistor which are connected in series, wherein the second transistor is far away from a first node compared with the first transistor, through adjustment of the second transistor, the leakage current of the second transistor is larger than that of the first transistor in the working process of the pixel driving circuit, so that when the first transistor and the second transistor are in a closed state, the leakage current leaks to the outer side far away from the first node through the second transistor, thereby reducing or even eliminating the potential change of the first node in the whole process that a light-emitting element is in a light-emitting state, so that the driving current received by the light-emitting element in the light-emitting state is in a stable state, and the light-emitting element is beneficial to keeping a stable light-emitting brightness in the light-emitting state, the problem of continuous flicker of the picture is improved or eliminated.
Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.
Claims (10)
1. A pixel driving circuit, comprising:
a driving transistor, a light emitting element and at least one switching transistor module;
the driving transistor is used for driving the light-emitting element, and the grid electrode of the driving transistor is connected to a first node;
the switch transistor module comprises a first transistor and a second transistor, wherein a first pole of the first transistor is connected to the first node, and a second pole of the first transistor is connected to a first pole of the second transistor;
the leakage current of the second transistor is greater than the leakage current of the first transistor.
2. The pixel driving circuit according to claim 1,
the grid electrode of the first transistor and the grid electrode of the second transistor are electrically connected to the same circuit control end.
3. The pixel driving circuit according to claim 1,
the second transistor has a first current-voltage characteristic when a voltage difference between the first electrode and the control electrode is a first voltage difference, and has a second current-voltage characteristic when the voltage difference between the first electrode and the control electrode is a second voltage difference;
wherein the second pressure differential is greater than the first pressure differential.
4. The pixel driving circuit according to claim 1,
the switching transistor module includes a first switching transistor module for transmitting a reference voltage to the first node.
5. The pixel driving circuit according to claim 1,
the switch transistor module comprises a second switch transistor module, and the second switch transistor module is connected between the grid electrode of the driving transistor and the second pole of the driving transistor.
6. The pixel driving circuit according to claim 1,
the first transistor comprises a first active layer, a first grid insulating layer and a first grid which are arranged in sequence;
the second transistor comprises a second active layer, a second grid electrode insulating layer and a second grid electrode which are arranged in sequence;
the density of interface defect states of a side of the second gate insulating layer facing the second gate is greater than the density of interface defect states of a side of the first gate insulating layer facing the first gate.
7. The pixel driving circuit according to claim 1,
the first transistor comprises a first light shielding layer, a first insulating layer, a first active layer, a first grid insulating layer and a first grid which are sequentially arranged;
the second transistor comprises a second light shielding layer, a second insulating layer, a second active layer, a second grid insulating layer and a second grid which are sequentially arranged;
the first light shielding layer is electrically connected with the first grid electrode, and the second light shielding layer is floating in potential.
8. The pixel driving circuit according to claim 1,
the channel length of the second transistor is smaller than the channel length of the first transistor.
9. A display panel comprising the pixel drive circuit according to any one of claims 1 to 8.
10. A display device characterized by comprising the display panel according to claim 9.
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| CN202111504572.XA CN114220382B (en) | 2021-12-10 | 2021-12-10 | Pixel driving circuit, display panel and display device |
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| CN114220382B (en) | 2023-05-05 |
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