Patent Application
20190340979
The present application claims a priority of the Chinese patent application No. 201610975825.4 filed on Oct. 28, 2016, which is incorporated herein by reference in its entirety.
The present disclosure relates to the field of display driving technology, in particular to a pixel driving circuit, a method for driving the pixel driving circuit and a display device.
In the related art, it is merely able for a pixel driving circuit to set a display resolution of a display panel, rather than to adjust the resolution or provide a low power mode. In addition, a large number of data lines and transistors are adopted by a conventional single-pixel compensation driving circuit, so it is unable to reduce a pixel pitch, and thereby it is unable to acquire higher image quality and higher Pixels Per Inch (PPI).
A main object of the present disclosure is to provide a pixel driving circuit, a method for driving the pixel driving circuit and a display device, so as to solver the above-mentioned problems.
In one aspect, the present disclosure provides in some embodiments a pixel driving circuit, including a driving control unit, a light-emission control signal generation unit and a pixel driving unit. The pixel driving unit includes N pixel driving sub-units connected to a same data line. The driving control unit is configured to generate a low resolution control signal or a high resolution control signal. The light-emission control signal generation unit is connected to the driving control unit and M*N light-emission control lines and configured to generate a corresponding light-emission control signal for each of the M*N light-emission control lines in accordance with the low resolution control signal or the high resolution control signal. Each of the pixel driving sub-units is connected to M light-emitting elements, a scanning line and M light-emission control lines and configured to, under the control of a data write-in control signal from the scanning line and the light-emission control signal from each of the M light-emission control lines, control the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously in accordance with a same data voltage applied to the data line when the light-emission control signal generation unit has received the low resolution control signal, and control the M light-emitting elements to emit light in a time-division manner in accordance with the M data voltages applied to the data line in a time-division manner when the light-emission control signal generation unit has received the high resolution control signal. N and M are both integers greater than 1.
In a possible embodiment of the present disclosure, each pixel driving sub-unit includes a driving transistor and a pixel driving control module connected to each other. The driving transistor is connected to the M light-emitting elements through the pixel driving control module. The pixel driving control module is further connected to the scanning line and the M light-emission control lines and configured to, under the control of the data write-in control signal from the scanning line and the light-emission control signal from each of the M light-emission control lines, enable the driving transistor to drive the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously in accordance with a same data voltage applied to the data line when the light-emission control signal generation unit has received the low resolution control signal, and enable, in a time-division manner, the driving transistor to drive the M light-emitting elements to emit light in a time-division manner in accordance with M data voltages applied to the data line in a time-division manner when the light-emission control signal generation unit has received the high resolution control signal.
In a possible embodiment of the present disclosure, an nth pixel driving control module includes: an nth resetting sub-module connected to a resetting end, an nth start signal output end and a gate electrode of an nth driving transistor and configured to enable the nth start signal output end to be electrically connected to the gate electrode of the nth driving transistor under the control of a resetting control signal from the resetting end; an nth charging/discharging sub-module, a first end of which is connected to a voltage output end, and a second end of which is connected to the gate electrode of the nth driving transistor; an nth compensation sub-module connected to an nth scanning line, the data line, the gate electrode of the nth driving transistor, and a first electrode and a second electrode of the nth driving transistor, and configured to, under the control of an nth data write-in control signal from the nth scanning line, apply the data voltage from the data line to the second electrode of the nth driving transistor and enable the gate electrode of the nth driving transistor to be electrically connected to the first electrode of the nth driving transistor, so as to charge or discharge the nth charging/discharging sub-module; an nth driving control sub-module connected to a driving control line, a high level output end and the first electrode of the nth driving transistor, and configured to, under the control of a driving control signal from the driving control line, enable the first electrode of the nth driving transistor to be electrically connected to the high level output end; and an nth light-emission control sub-module connected to the M light-emitting elements and M light-emission control lines, and configured to, under the control of the light-emission control signal from each of the M light-emission control lines, enable the nth driving transistor to drive the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously in accordance with a same data voltage applied to the data line when the light-emission control signal generation unit has received the low resolution control signal, and enable, in a time-division manner, the nth driving transistor to drive the M light-emitting elements to emit light in a time-division manner in accordance with M data voltages applied to the data line in a time-division manner when the light-emission control signal generation unit has received the high resolution control signal, where n is a positive integer greater than or equal to 1 and smaller than or equal to N.
In a possible embodiment of the present disclosure, the nth compensation sub-module includes: a first compensation transistor, a gate electrode of which is connected to the nth scanning line, a first electrode of which is connected to the data line, and a second electrode of which is connected to the second electrode of the nth driving transistor; and a second compensation transistor, a gate electrode of which is connected to the nth scanning line, a first electrode of which is connected to the gate electrode of the nth driving transistor, and a second electrode of which is connected to the first electrode of the nth driving transistor.
In a possible embodiment of the present disclosure, the nth driving control sub-module includes an nth driving control transistor, a gate electrode of which is connected to the driving control line, a first electrode of which is connected to the high level output end, and a second electrode of which is connected to the first electrode of the nth driving transistor. The nth light-emission control sub-module includes M light-emission control transistors. A gate electrode of each light-emission control transistor is connected to one of the light-emission control lines, a first electrode thereof is connected to the second electrode of the nth driving transistor, and a second electrode thereof is connected to one of the light-emitting elements.
In a possible embodiment of the present disclosure, the resetting sub-module includes a resetting transistor, a gate electrode of which is connected to the resetting end, a first electrode of which is connected to the nth start signal output end, and a second electrode of which is connected to the gate electrode of the nth driving transistor. The nth charging/discharging sub-module includes an nth storage capacitor, a first end of which is connected to a voltage output end, and a second end of which is connected to the gate electrode of the nth driving transistor.
In a possible embodiment of the present disclosure, when the nth driving transistor is a p-type transistor, a difference between an nth start signal from the nth start signal output end and a data voltage outputted by the data line under the control of the nth data write-in control signal from the nth scanning line is smaller than a threshold voltage of the nth driving transistor.
In a possible embodiment of the present disclosure, when the nth driving transistor is an n-type transistor, a difference between an nth start signal from the nth start signal output end and a data voltage outputted by the data line under the control of the nth data write-in control signal from the nth scanning line is greater than or equal to a threshold voltage of the nth driving transistor.
In a possible embodiment of the present disclosure, when the nth charging/discharging sub-module stops to be charged or discharged, a potential at the gate electrode of the nth driving transistor is equal to a sum of the data voltage and the threshold voltage of the nth driving transistor.
In a possible embodiment of the present disclosure, the pixel driving control module is further configured to, when the driving transistor drives the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously or in a time-division manner, compensate for the threshold voltage of the driving transistor.
In a possible embodiment of the present disclosure, the pixel driving control module is further configured to compensate for the threshold voltage of the driving transistor with a gate-to-source voltage of the driving transistor.
In a possible embodiment of the present disclosure, the light-emitting element is an organic light-emitting diode (OLED), an anode of which is connected to the pixel driving sub-unit, and a cathode of which is grounded.
In a possible embodiment of the present disclosure, the driving control unit is configured to generate the low resolution control signal or the high resolution control signal in accordance with an external distance, and the external distance is a distance between a human eye and a display panel.
In another aspect, the present disclosure provides in some embodiments a method for driving the above-mentioned pixel driving circuit, including: a display control signal generation step of generating, by the driving control unit, a low resolution control signal or a high resolution control signal, and transmitting the low resolution control signal or the high resolution control signal to the light-emission control signal generation unit; a light-emission control signal generation step of generating, by the light-emission control signal generation unit, a corresponding light-emission control signal for each of M*N light-emission control lines in accordance with the low resolution control signal or the high resolution control signal; and a display driving step of, under the control of a data write-in control signal from a scanning line and the light-emission control signal from each of the M light-emission control lines, enabling, by each of the pixel driving sub-units, the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously in accordance with a same data voltage applied to the data line when the light-emission control signal generation unit has received the low resolution control signal, or enabling, by each of the pixel driving sub-units, the M light-emitting elements to emit light in a time-division manner in accordance with M data voltages applied to the data line in a time-division manner when the light-emission control signal generation unit has received the high resolution control signal, where N and M are both integers greater than 1.
In a possible embodiment of the present disclosure, each pixel driving sub-unit includes a driving transistor and a pixel driving control module connected to each other and the driving transistor is connected to the M light-emitting elements through the pixel driving control module, the display driving step includes: when the light-emission control signal generation unit has received the low resolution control signal, under the control of the data write-in control signal from the scanning line and the light-emission control signal from each of the M light-emission control lines, enabling, by the pixel driving control module, the driving transistor to drive the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously in accordance with a same data voltage applied to the data line; or when the light-emission control signal generation unit has received the high resolution control signal, under the control of the data write-in control signal from the scanning line and the light-emission control signal from each of the M light-emission control lines, enabling, by the pixel driving control module, the driving transistor to drive the M light-emitting elements to emit light in a time-division manner in accordance with M data voltages applied to the data line in a time-division manner.
In a possible embodiment of the present disclosure, the display driving step further includes, when the driving transistor drives the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously or in a time-division manner, compensating for a threshold voltage of the driving transistor with a gate-to-source voltage of the driving transistor.
In a possible embodiment of the present disclosure, the display driving step further includes: enabling, by an nth resetting sub-module, an nth start signal output end to be electrically connected to a gate electrode of an nth driving transistor under the control of a resetting control signal from a resetting end; under the control of an nth data write-in control signal from an nth scanning line, applying, by an nth compensation sub-module, a data voltage from the data line to a second electrode of the nth driving transistor and enabling the gate electrode of the nth driving transistor to be electrically connected to a first electrode of the nth driving transistor, so as to charge or discharge an nth charging/discharging sub-module; enabling, by an nth driving control sub-module, the first electrode of the nth driving transistor to be electrically connected to a high level output end under the control of a driving control signal from a driving control line; and under the control of the light-emission control signal from each of the M light-emission control lines, enabling, by an nth light-emission control sub-module, the nth driving transistor to drive the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously in accordance with a same data voltage applied to the data line when the light-emission control signal generation unit has received the low resolution control signal, or enabling, by the nth light-emission control sub-module, the nth driving transistor to drive the M light-emitting elements to emit light in a time-division manner in accordance with M data voltages applied to the data line in a time-division manner when the light-emission control signal generation unit has received the high resolution control signal.
In a possible embodiment of the present disclosure, each display period includes M display sub-periods. Each display sub-period includes a resetting stage, a compensation stage and a light-emission stage. The compensation stage includes N compensation time periods, and the light-emission stage includes N light-emission time periods. The display driving step further includes, when the light-emission control signal generation unit has received the high resolution control signal, within an mth display sub-period: at the resetting stage, enabling, by the resetting sub-module, a gate electrode of a corresponding driving transistor to receive a corresponding start signal under the control of the resetting control signal from the resetting end; within an nth compensation time period of the compensation stage, under the control of an nth data write-in control signal from the nth scanning line, applying, by the nth compensation sub-module, the data voltage from the data line to the second electrode of the nth driving transistor, and enabling the gate electrode of the nth driving transistor to be electrically connected to the first electrode of the nth driving transistor, so as to charge or discharge the nth charging/discharging sub-module until a potential at the gate electrode of the nth driving transistor is equal to a sum of the data voltage and the threshold voltage of the nth driving transistor; and within an nth light-emission time period of the light-emission stage, enabling, by the nth driving control sub-module, the first electrode of the nth driving transistor to be electrically connected to the high level output end under the control of the driving control signal from the driving control line, and under the control of an mth light-emission control signal from an mth light-emission control line, enabling, by the nth light-emission control sub-module, the nth driving transistor to drive an mth light-emitting element connected to the nth pixel driving control module to emit light in accordance with the data voltage, and compensating for the threshold voltage of the nth driving transistor with the gate-to-source voltage of the nth driving transistor, where m is an integer greater than or equal to 1 and smaller than or equal to M.
In a possible embodiment of the present disclosure, each display period includes M display sub-periods. Each display sub-period includes a resetting stage, a compensation stage and a light-emission stage. The compensation stage includes N compensation time periods, and the light-emission stage incudes N light-emission time periods. The display driving step further includes, when the light-emission control signal generation unit has received the low resolution control signal, within an mth display sub-period: at the resetting stage, enabling, by the resetting sub-module, a gate electrode of a corresponding driving transistor to receive a corresponding start signal under the control of the resetting control signal from the resetting end; within an nth compensation time period of the compensation stage, under the control of an nth data write-in control signal from the nth scanning line, applying, by the nth compensation sub-module, the data voltage from the data line to the second electrode of the nth driving transistor, and enabling the gate electrode of the nth driving transistor to be electrically connected to the first electrode of the nth driving transistor, so as to charge or discharge the nth charging/discharging sub-module until a potential at the gate electrode of the nth driving transistor is equal to a sum of the data voltage and the threshold voltage of the nth driving transistor; and within an nth light-emission time period of the light-emission stage, enabling, by the nth driving control sub-module, the first electrode of the nth driving transistor to be electrically connected to the high level output end under the control of the driving control signal from the driving control line, and under the control of the M light-emission control signals from the M light-emission control lines, enabling, by the nth light-emission control sub-module, the M light-emitting elements connected to the nth pixel driving control module to emit light simultaneously in accordance with the data voltage, and compensating for the threshold voltage of the nth driving transistor with the gate-to-source voltage of the nth driving transistor, where m is an integer greater than or equal to 1 and smaller than or equal to M.
In a possible embodiment of the present disclosure, the display control signal generation step further includes generating, by the driving control unit, the low resolution control signal or the high resolution control signal in accordance with an external distance. The external distance is a distance between a human eye and a display panel.
In yet another aspect, the present disclosure provides in some embodiments a display device including a display panel and the above-mentioned pixel driving circuit.
In a possible embodiment of the present disclosure, the display device further includes a human eye detection unit connected to a driving control unit of the pixel driving circuit and configured to detect a distance between a human eye and the display panel and transmit the distance to the driving control unit. The driving control unit is configured to, when the distance is greater than or equal to a predetermined distance, transmit a low resolution control signal to the pixel driving unit, and when the distance is smaller than the predetermined distance, transmit a high resolution control signal to the pixel driving unit.
In order to make the objects, the technical solutions and the advantages of the present disclosure more apparent, the present disclosure will be described hereinafter in a clear and complete manner in conjunction with the drawings and embodiments. Obviously, the following embodiments merely relate to a part of, rather than all of, the embodiments of the present disclosure, and based on these embodiments, a person skilled in the art may, without any creative effort, obtain the other embodiments, which also fall within the scope of the present disclosure.
The present disclosure provides in some embodiments a pixel driving circuit, which includes a driving control unit, a light-emission control signal generation unit and a pixel driving unit. The driving control unit is configured to generate a low resolution control signal or a high resolution control signal. In a possible embodiment of the present disclosure, the driving control unit may generate the low resolution control signal or the high resolution control signal in accordance with an external distance, and the external distance is a distance between a human eye and a display panel. The light-emission control signal generation unit is connected to the driving control unit and M*N light-emission control lines and configured to generate a corresponding light-emission control signal for each of the M*N light-emission control lines in accordance with the low resolution control signal or the high resolution control signal. The pixel driving unit includes N pixel driving sub-units connected to a same data line. Each of the pixel driving sub-units is connected to M light-emitting elements, a corresponding scanning line and corresponding M light-emission control lines and configured to, under the control of a data write-in control signal from the scanning line and the light-emission control signals from the M light-emission control lines, control the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously in accordance with a same data voltage applied to the data line when the light-emission control signal generation unit has received the low resolution control signal, and control the M light-emitting elements to emit light in a time-division manner in accordance with the M data voltages applied to the data line in a time-division manner when the light-emission control signal generation unit has received the high resolution control signal. N and M are both integers greater than 1.
Under the control of the low resolution control signal, the pixel driving circuit is in a low resolution display mode, and at this time, the resolution is smaller than or equal to a resolution threshold. Under the control of the high resolution control signal, the pixel driving circuit is in a high resolution display mode, and at this time, the resolution is greater than the resolution threshold.
According to the pixel driving circuit in the embodiments of the present disclosure, it is able to intelligently adjust the resolution, thereby to dynamically and intelligently adjust a resolution of the display panel, and provide a low power mode. In addition, pixels in a plurality of columns are controlled by a same data line, and one pixel driving circuit is used to drive a plurality of pixels, so as to reduce the number of compensation thin film transistors (TFTs), remarkably reduce the pixel pitch and acquire higher image quality and higher PPI.
In actual use, the driving control unit of the pixel driving circuit may generate the low resolution control signal or the high resolution control signal in accordance with the distance between the human eye and the display panel, or in accordance with any other situations where the resolution needs to be adjusted. Then, the light-emission control signal generation unit may generate the corresponding light-emission control signal in accordance with the corresponding resolution control signal. When it is necessary to display an image at a high resolution, the pixel driving sub-unit may control, in a time-division manner, the M light-emitting elements (which are adjacently arranged in a same column) to emit light in a time-division manner in accordance with the M data voltages applied to the data line in a time-division manner. When it is merely necessary to display the image at a low resolution, the pixel driving sub-unit may control the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously in accordance with the same data voltage applied to the data line, so as to effectively reduce the power consumption of the display panel while ensuring a display effect, thereby to selectively switch the resolution for the display panel and enable the resolution to be adjustable.
In actual use, the light-emitting element may be an Organic Light-Emitting Diode (OLED), or any other light-emitting member.
The pixel driving circuit in the embodiments of the present disclosure will be described hereinafter in conjunction with the drawings when N and M are each 2.
As shown in
In a possible embodiment of the present disclosure, the driving control unit may generate the low resolution control signal or the high resolution control signal in accordance with the distance between the human eye and the display panel. To be specific, the driving control unit may be configured to transmit the low resolution control signal to the pixel driving unit when the external distance is greater than or equal to a predetermined distance, and transmit the high resolution control signal to the pixel driving unit when the external distance is smaller than the predetermined distance.
In actual use, the predetermined distance may be set according to the practical need, e.g., in accordance with a requirement on the resolution of the display panel and a size of the display panel. For example, when the display panel is of a small size, the predetermined distance may have a relatively small value, and when the display panel is of a large size, the predetermined distance may have a relatively large value. In addition, when a display effect (e.g., the resolution) of the display panel is highly demanded, the predetermined distance may have a relatively large value, and when the display effect of the display panel is not so highly demanded, the predetermined distance may have a relatively small value.
In a possible embodiment of the present disclosure, each pixel driving sub-unit includes a driving transistor and a pixel driving control module connected to each other. The driving transistor is connected to the M light-emitting elements through the pixel driving control module. The pixel driving control module is further connected to the corresponding scanning line and the M light-emission control lines and configured to, under the control of the data write-in control signal from the scanning line and the light-emission control signals from the M light-emission control lines, when the light-emission control signal generation unit has received the low resolution control signal, enable the driving transistor to drive the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously in accordance with a same data voltage applied to the data line and compensate for a threshold voltage of the driving transistor with a gate-to-source voltage of the driving transistor, and when the light-emission control signal generation unit has received the high resolution control signal, enable, in a time-division manner, the driving transistor to drive the M light-emitting elements to emit light in a time-division manner in accordance with M data voltages applied to the data line in a time-division manner and compensate for a threshold voltage of the driving transistor with a gate-to-source voltage of the driving transistor.
When the light-emission control signal generation unit has received the high resolution control signal or the low resolution control signal, the pixel driving control module is further configured to compensate for the threshold voltage while driving the light-emitting elements to emit light. As a result, it is able to prevent the occurrence of display non-uniformity due to the drift of the threshold voltage of the driving TFT caused by a manufacture process or long-term operation, and prevent the current flowing through each pixel point OLED from being adversely affected by the threshold voltage of the driving transistor, thereby to ensure the display uniformity of the image.
In a possible embodiment of the present disclosure, an nth pixel driving control module may include: an nth resetting sub-module connected to a resetting end, an nth start signal output end and a gate electrode of an nth driving transistor connected to the nth pixel driving control module, and configured to enable the nth start signal output end to be electrically connected to the gate electrode of the nth driving transistor under the control of a resetting control signal from the resetting end; an nth charging/discharging sub-module, a first end of which is connected to a voltage output end, and a second end of which is connected to the gate electrode of the nth driving transistor; an nth compensation sub-module connected to an nth scanning line, the data line, the gate electrode of the nth driving transistor, and a first electrode and a second electrode of the nth driving transistor, and configured to, under the control of an nth data write-in control signal from the nth scanning line, apply the data voltage from the data line to the second electrode of the nth driving transistor and enable the gate electrode of the nth driving transistor to be electrically connected to the first electrode of the nth driving transistor, so as to charge or discharge the nth charging/discharging sub-module until a potential at the gate electrode of the nth driving transistor is equal to a sum of the data voltage and a threshold voltage of the nth driving transistor; an nth driving control sub-module connected to a driving control line, a high level output end and the first electrode of the nth driving transistor, and configured to, under the control of a driving control signal from the driving control line, enable the first electrode of the nth driving transistor to be electrically connected to the high level output end; and an nth light-emission control sub-module connected to the M light-emitting elements and M light-emission control lines, and configured to, under the control of the light-emission control signals from the M light-emission control lines, when the light-emission control signal generation unit has received the low resolution control signal, enable the nth driving transistor to drive the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously in accordance with a same data voltage applied to the data line and compensate for the threshold voltage of the nth driving transistor with a gate-to-source voltage of the nth driving transistor, and when the light-emission control signal generation unit has received the high resolution control signal, enable, in a time-division manner, the nth driving transistor to drive the M light-emitting elements to emit light in a time-division manner in accordance with M data voltages applied to the data line in a time-division manner and compensate for the threshold voltage of the nth driving transistor with a gate-to-source voltage of the nth driving transistor, where n is a positive integer smaller than or equal to N.
To be specific, as shown in
In
In
To be specific, when the nth driving transistor is a p-type transistor, a difference between the nth start signal Vini-n from the nth start signal output end and a data voltage outputted by the data line under the control of the nth data write-in control signal from the nth scanning line Scan-n is smaller than the threshold voltage of the nth driving transistor. In this way, D-n may be turned on at the beginning of a compensation stage, and after the nth charging/discharging sub-module 22 is charged until the potential at the gate electrode of the nth driving transistor D-n is equal to a sum of the data voltage and the threshold voltage of the nth driving transistor D-n, D-n may be turned off and a charging operation may be ceased.
When the nth driving transistor is an n-type transistor, a difference between the nth start signal Vini-n from the nth start signal output end and a data voltage outputted by the data line under the control of the nth data write-in control signal from the nth scanning line Scan-n is greater than or equal to the threshold voltage of the nth driving transistor D-n. In this way, D-n may be turned on at the beginning of the compensation stage, and after the nth charging/discharging sub-module 22 is discharged until the potential at the gate electrode of the nth driving transistor D-n is equal to a sum of the data voltage and the threshold voltage of the nth driving transistor D-n, D-n may be turned off and a discharging operation may be ceased.
In actual use, Vg may have a value sufficient to enable, at the compensation stage, the potential at the gate electrode of the nth driving transistor to be equal to a sum of the data voltage and the threshold voltage of the nth driving transistor through the charging or discharging operation of the nth charging/discharging sub-module.
To be specific, the nth compensation sub-module may include: a first compensation transistor, a gate electrode of which is connected to the nth scanning line, a first electrode of which is connected to the data line, and a second electrode of which is connected to the second electrode of the nth driving transistor; and a second compensation transistor, a gate electrode of which is connected to the nth scanning line, a first electrode of which is connected to the gate electrode of the nth driving transistor, and a second electrode of which is connected to the first electrode of the nth driving transistor.
To be specific, the nth driving control sub-module may include an nth driving control transistor, a gate electrode of which is connected to the driving control line, a first electrode of which is connected to the high level output end, and a second electrode of which is connected to the first electrode of the nth driving transistor. The nth light-emission control sub-module includes M light-emission control transistors. A gate electrode of each light-emission control transistor is connected to one of the light-emission control lines, a first electrode thereof is connected to the second electrode of the nth driving transistor, and a second electrode thereof is connected to one of the light-emitting elements.
To be specific, the resetting sub-module may include a resetting transistor, a gate electrode of which is connected to the resetting end, a first electrode of which is connected to the nth start signal output end, and a second electrode of which is connected to the gate electrode of the nth driving transistor. The nth charging/discharging sub-module may include an nth storage capacitor, a first end of which is connected to a voltage output end, and a second end of which is connected to the gate electrode of the nth driving transistor.
The pixel driving circuit will be described hereinafter in more details.
As shown in
The first pixel driving sub-unit 31 includes a first driving transistor D1, a first resetting sub-module, a first charging/discharging sub-module, a first compensation sub-module, a first driving control sub-module and a first light-emission control sub-module.
The second pixel driving sub-unit 32 includes a second driving transistor D2, a second resetting sub-module, a second charging/discharging sub-module, a second compensation sub-module, a second driving control sub-module and a second light-emission control sub-module.
The pixel driving unit in
The first charging/discharging sub-module includes the first storage capacitor C1, a first end of which is connected to the high level output end for outputting Vdd.
The first resetting sub-module includes a fifth transistor T5, a gate electrode of which is connected to the resetting end Reset, a source electrode of which is connected to a second end of the first storage capacitor C1, and a drain electrode of which is configured to receive an initial voltage Vint.
The first compensation sub-module includes: a third transistor T3, a gate electrode of which is connected to a first scanning line Scan1, a source electrode of which is connected to a source electrode of D1, and a drain electrode of which is connected to the data line Data; and a seventh transistor T7, a gate electrode of which is connected to the first scanning line Scan1, and a source electrode of which is connected to a drain electrode of D1.
The first driving sub-module includes a first transistor T1, a gate electrode of which is connected to the driving control line EM, a source electrode of which is connected to the high level output end for outputting Vdd, and a drain electrode of which is connected to the source electrode of D1.
The first light-emission control sub-module includes: a ninth transistor T9, a gate electrode of which is connected to the first light-emission control line EM1, a source electrode of which is connected to the drain electrode of D1, and a drain electrode of which is connected to the anode of the first OLED OLED1; and a tenth transistor T10, a gate electrode of which is connected to the second light-emission control line EM2, a source electrode of which is connected to the drain electrode of D1, and a drain electrode of which is connected to the anode of the second OLED OLED2.
The second charging/discharging sub-module includes the second storage capacitor C2, a first end of which is connected to the high level output end for outputting Vdd.
The second resetting sub-module includes a sixth transistor T6, a gate electrode of which is connected to the resetting end Reset, a source electrode of which is connected to a second end of the second storage capacitor C2, and a drain electrode of which is configured to receive the initial voltage Vint.
The second compensation sub-module includes: a fourth transistor T4, a gate electrode of which is connected to the second scanning line Scan2, a source electrode of which is connected to the source electrode of D2, and a drain electrode of which is connected to the data line Data; and an eighth transistor T8, a gate electrode of which is connected to the second scanning line Scan2, and a source electrode of which is connected to the drain electrode of D2.
The second driving sub-module includes a second transistor T2, a gate electrode of which is connected to the driving control line EM, a source electrode of which is connected to the high level output end for outputting Vdd, and a drain electrode of which is connected to the source electrode of D2.
The second light-emission control sub-module includes: an eleventh transistor T11, a gate electrode of which is connected to the third light-emission control line EM3, a source electrode of which is connected to the drain electrode of D2, and a drain electrode of which is connected to an anode of the third OLED OLED3; and a twelfth transistor T12, a gate electrode of which is connected to the fourth light-emission control line EM4, a source electrode of which is connected to the drain electrode of D2, and a drain electrode of which is connected to an anode of the fourth OLED OLED4.
Cathodes of OLED1, OLED2, OLED3 and OLED4 are connected to the grounding end GND.
OLED1 is an OLED of a first pixel P1 in a first row and a first column, OLED2 is an OLED of a second pixel P2 in a second row and the first column, OLED3 is an OLED of a third pixel P3 in the first row and a second column, and OLED4 is an OLED of a fourth pixel P4 in the second row and the second column.
In
In
As shown in
As shown in
As shown in
As shown in
I
OLED1
=K1*(VGS1−Vth1)2=K1*[Vdd−(V1−Vth1)−Vth1]2=K1*(Vdd−V1)2,
where K1 represents a current coefficient of D1, and VGS1 represents a gate-to-source voltage of D1 at T1-4.
As can be seen from the above equation, IOLED1 is merely related to V1 but irrelevant to Vth1. As a result, it is able to prevent an operating current of the OLED from being adversely affected due to the drift of the threshold voltage of the driving TFT caused by a manufacture process or long-term operation, thereby to ensure the normal operation of OLED1.
As shown in
I
OLED3
=K2*(VGS2−Vth2)2=K2*[Vdd−(V3−Vth2)−Vth2]2=K2*(Vdd−V3)2,
where K2 represents a current coefficient of D2, and VGS2 represents a gate-to-source voltage of D2 at T1-5.
As can be seen from the above equation, IOLED3 is merely related to V3 but irrelevant to Vth2. As a result, it is able to prevent an operating current of the OLED from being adversely affected due to the drift of the threshold voltage of the driving TFT caused by a manufacture process or long-term operation, thereby to ensure the normal operation of OLED3.
As shown in
At a third compensation stage T2-2, i.e., a second pixel charging stage, Scan2 outputs a low level, so as to turn on T4 and T8, thereby to charge the second pixel P2. At this time, Data outputs a second data voltage V2, so after the charging operation, a potential at a1 is V2+Vth1, and a potential at b1 is Vdd, where Vth1 represents the threshold voltage of D1. In
At a fourth compensation stage T2-3, i.e., a fourth pixel charging stage, Scan2 outputs a low level, so as to turn on T4 and T8. At this time, Data outputs a fourth data voltage V4, so after the charging operation, a potential at a2 is V4+Vth2, and a potential at b2 is Vdd, where Vth2 represents the threshold voltage of D2. In
As shown in
I
OLED2
=K1*(VGS3−Vth1)2=K1*[Vdd−(V2−Vth1)−Vth1]2=K1*(Vdd−V2)2,
where K1 represents a current coefficient of D1, and VGS3 represents a gate-to-source voltage of D1 at T2-4.
As can be seen from the above equation, IOLED2 is merely related to V2 but irrelevant to Vth1. As a result, it is able to prevent an operating current of the OLED from being adversely affected due to the drift of the threshold voltage of the driving TFT caused by a manufacture process or long-term operation, thereby to ensure the normal operation of OLED2.
As shown in
I
OLED4
=K2*(VGS4−Vth2)2=K2*[Vdd−(V4−Vth2)−Vth2]2=K2*(Vdd−V4)2,
where K2 represents a current coefficient of D2, and VGS4 represents a gate-to-source voltage of D2 at T2-5.
As can be seen from the above equation, IOLED4 is merely related to V4 but irrelevant to Vth1. As a result, it is able to prevent an operating current of the OLED from being adversely affected due to the drift of the threshold voltage of the driving TFT caused by a manufacture process or long-term operation, thereby to ensure the normal operation of OLED4.
As mentioned above, when the pixel driving circuit is in the high resolution display mode, within the first time period T1, the first pixel P1 may emit light in accordance with V1, and then the third pixel P3 may emit light in accordance with V3. Within the second time period T2, the second pixel P2 may emit light in accordance with V2, and the fourth pixel P4 may emit light in accordance with V4.
As shown in
The present disclosure further provides in some embodiments a method for driving the above-mentioned pixel driving circuit which, as shown in
In a possible embodiment of the present disclosure, the method for driving the above-mentioned pixel driving circuit includes: a display control signal generation step of generating, by the driving control unit of the pixel driving circuit, the low resolution control signal or the high resolution control signal in accordance with an external distance, the external distance being a distance between a human eye and a display panel; a light-emission control signal generation step of generating, by the light-emission control signal generation unit of the pixel driving circuit, a corresponding light-emission control signal for each of M*N light-emission control lines in accordance with the low resolution control signal or the high resolution control signal; and a display driving step of, under the control of a data write-in control signal from a scanning line and the light-emission control signal from each of the M light-emission control lines, when the light-emission control signal generation unit has received the low resolution control signal, enabling, by each pixel driving sub-unit of the pixel driving unit, the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously in accordance with a same data voltage applied to the data line , or when the light-emission control signal generation unit has received the high resolution control signal, enabling, by each pixel driving sub-unit of the pixel driving unit, the M light-emitting elements to emit light in a time-division manner in accordance with M data voltages applied to the data line in a time-division manner , where N and M are both integers greater than 1.
In a possible embodiment of the present disclosure, the display control signal generation step further includes: generating, by the driving control unit, the low resolution control signal or the high resolution control signal in accordance with a distance between a human eye and a display panel; when the distance is greater than or equal to a predetermined distance, transmitting, by the driving control unit, the low resolution control signal to the pixel driving unit; and when the distance is smaller than the predetermined distance, transmitting, by the driving control unit, the high resolution control signal to the pixel driving unit.
To be specific, when each pixel driving sub-unit includes a driving transistor and a pixel driving control module connected to each other and the driving transistor is connected to the M light-emitting elements through the pixel driving control module, the display driving step includes: when the light-emission control signal generation unit has received the low resolution control signal, under the control of the data write-in control signal from the scanning line and the light-emission control signal from each of the M light-emission control lines, enabling, by the pixel driving control module, the driving transistor to drive the M light-emitting elements connected to the pixel driving sub-unit to emit light simultaneously in accordance with a same data voltage applied to the data line and compensate for a threshold voltage of the driving transistor with a gate-to-source voltage of the driving transistor; or when the light-emission control signal generation unit has received the high resolution control signal, under the control of the data write-in control signal from the scanning line and the light-emission control signal from each of the M light-emission control lines, enabling, by the pixel driving control module, the driving transistor to drive the M light-emitting elements to emit light in a time-division manner in accordance with M data voltages applied to the data line in a time-division manner and compensate for the threshold voltage of the driving transistor with the gate-to-source voltage of the driving transistor.
To be specific, each display period includes M display sub-periods. An nth pixel driving control module includes a resetting sub-module, an nth charging/discharging sub-module, an nth compensation sub-module, an nth driving control sub-module and an nth light-emission control sub-module. When the light-emission control signal generation unit has received the high resolution control signal, each display sub-period includes a resetting stage, a compensation stage and a light-emission stage. The compensation stage includes N compensation time periods, and the light-emission stage includes N light-emission time periods. Within an mth display sub-period, the display driving step may include: a resetting step of, at the resetting stage, enabling, by the resetting sub-module, a gate electrode of a corresponding driving transistor to receive a corresponding start signal under the control of the resetting control signal from the resetting end; a compensation step of, within an nth compensation time period of the compensation stage, under the control of an nth data write-in control signal from the nth scanning line, applying, by the nth compensation sub-module, the data voltage from the data line to the second electrode of the nth driving transistor, and enabling the gate electrode of the nth driving transistor to be electrically connected to the first electrode of the nth driving transistor, so as to charge or discharge the nth charging/discharging sub-module until a potential at the gate electrode of the nth driving transistor is equal to a sum of the data voltage and the threshold voltage of the nth driving transistor; and a light-emission stage of, within an nth light-emission time period of the light-emission stage, enabling, by the nth driving control sub-module, the first electrode of the nth driving transistor to be electrically connected to the high level output end under the control of the driving control signal from the driving control line, and under the control of an mth light-emission control signal from an mth light-emission control line, enabling, by the nth light-emission control sub-module, the nth driving transistor to drive an mth light-emitting element connected to the nth pixel driving control module to emit light in accordance with the data voltage, and compensating for the threshold voltage of the nth driving transistor with the gate-to-source voltage of the nth driving transistor, where n is a positive integer smaller than or equal to N, and m is an integer smaller than or equal to M.
To be specific, each display period includes M display sub-periods. Each display sub-period includes a resetting stage, a compensation stage and a light-emission stage. An nth pixel driving control module includes a resetting sub-module, an nth charging/discharging sub-module, an nth compensation sub-module, an nth driving control sub-module and an nth light-emission control sub-module. When the light-emission control signal generation unit has received the low resolution control signal, each display sub-period includes a resetting stage, a compensation stage and a light-emission stage in turns. The compensation stage includes N compensation time periods, and the light-emission stage includes N light-emission time periods. Within an mth display sub-period, the display driving step may include: a resetting step of, at the resetting stage, enabling, by the resetting sub-module, a gate electrode of a corresponding driving transistor to receive a corresponding start signal under the control of the resetting control signal from the resetting end; a compensation step of, within an nth compensation time period of the compensation stage, under the control of an nth data write-in control signal from the nth scanning line, applying, by the nth compensation sub-module, the data voltage from the data line to the second electrode of the nth driving transistor, and enabling the gate electrode of the nth driving transistor to be electrically connected to the first electrode of the nth driving transistor, so as to charge or discharge the nth charging/discharging sub-module until a potential at the gate electrode of the nth driving transistor is equal to a sum of the data voltage and the threshold voltage of the nth driving transistor; and a light-emission step of, within an nth light-emission time period of the light-emission stage, enabling, by the nth driving control sub-module, the first electrode of the nth driving transistor to be electrically connected to the high level output end under the control of the driving control signal from the driving control line, and under the control of the M light-emission control signals from the M light-emission control lines, enabling, by the nth light-emission control sub-module, the M light-emitting elements connected to the nth pixel driving control module to emit light simultaneously in accordance with the data voltage, and compensating for the threshold voltage of the nth driving transistor with the gate-to-source voltage of the nth driving transistor, where n is a positive integer smaller than or equal to N, and m is an integer smaller than or equal to M.
The present disclosure further provides in some embodiments a display device including a display panel and the above-mentioned pixel driving circuit.
To be specific, the display device may further include a human eye detection unit connected to a driving control unit of the pixel driving circuit and configured to detect a distance between a human eye and the display panel and transmit the distance to the driving control unit. The driving control unit is configured to, when the distance is greater than or equal to a predetermined distance, transmit a low resolution control signal to the pixel driving unit, and when the distance is smaller than the predetermined distance, transmit a high resolution control signal to the pixel driving unit.
The pixel driving circuit may be a silicon-based OLED back plate driving circuit with a Smart View display mode.
According to the embodiments of the present disclosure, based on the silicon-based OLED display technology, it is able to adjust the resolution with respect to a region capable of being viewed by the human eye, thereby to reduce the power consumption. In addition, every two adjacent single-pixel compensation units known in the art may share a same data line (i.e., two compensation circuits are controlled by one data line), so it is able to reduce the number of the compensation TFTs, thereby to remarkably reduce the Pixel Pitch and acquire higher image quality and higher PPI.
In addition, through the detection unit, it is able to accurately determine a position of the human eye and the distance between the human eye and the display panel. When the human eye is close to the display panel, the display panel may be in a high resolution mode, and when the human eye is far away from the display panel, the display panel may be in a low resolution mode. As a result, it is able to selectively switch the resolution, thereby to effectively reduce the power consumption of the display panel.
The above are merely the preferred embodiments of the present disclosure, but the present disclosure is not limited thereto. Obviously, a person skilled in the art may make further modifications and improvements without departing from the spirit of the present disclosure, and these modifications and improvements shall also fall within the scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201610975825.4 | Oct 2016 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2017/090539 | 6/28/2017 | WO | 00 |
