Patent Grant
10176766
The present disclosure relates to a display driving method and apparatus and a display device comprising the display driving apparatus.
In order to prolong service time of a mobile product, there is proposed a low frequency drive technique at present. Such low frequency drive technique reduces power consumption of the mobile product which are displaying by reducing refresh frequency of the display device. However, such technique would prolong the time of one frame. In actual application, due to existence of leakage current, pixel voltage in a liquid crystal display device would gradually drop with time. This would lead to change of luminance. For example, for a display driving device in a normally black mode, as a pixel voltage within one frame declines gradually, it would cause display luminance decrease gradually, thereby resulting in picture flicker. Such a phenomenon is particularly evident in the liquid crystal display device that adopts the low frequency drive technique.
There are provided in some embodiments of the present disclosure a display driving method, a display driving apparatus and a display device comprising the display driving apparatus. According to a first aspect of the present disclosure, there is provided a display driving method, comprising:
determining whether scanning of at least one area of display areas is completed;
adjusting light-emitting luminance of display light source corresponding to the at least one area after scanning of the at least one area is completed, such that display luminance of the at least one area maintains within a specified range.
Further, in the case of driving a liquid crystal display device in a normally black mode, the adjusting light-emitting luminance of display light source corresponding to the at least one area includes: adjusting light-emitting luminance of display light source corresponding to the at least one area according to following luminance adjustment formula:
Ct:Ct=C0*et/τ;
where C0 is light-emitting luminance of display light source corresponding to the at least one area at an adjustment starting moment, t is time length between a current moment and the adjustment starting moment, and τ is a product of a pixel leakage resistance and a pixel capacitance.
Further, in the case of driving a liquid crystal display device in a normally white mode, the adjusting light-emitting luminance of display light source corresponding to the at least one area comprises: adjusting light-emitting luminance of display light source corresponding to the at least one area according to following luminance adjustment formula:
Ct:Ct=C0*e−t/τ;
where C0 is light-emitting luminance of display light source corresponding to the at least one area at an adjustment starting moment, t is time length between a current moment and the adjustment starting moment, and τ is a product of a pixel leakage resistance and a pixel capacitance.
Further, the adjusting light-emitting luminance of display light source corresponding to the at least one area comprises:
adjusting light-emitting luminance of display light source corresponding to the at least one area by means of pulse width modulation.
Further, the display area comprises a plurality of areas, each of which is corresponding to an independent group of display light sources;
The adjusting light-emitting luminance of display light source corresponding to the at least one area comprises:
adjusting light-emitting luminance of display light source corresponding to each area sequentially in a scanning order of each area.
Further, the adjusting light-emitting luminance of display light source corresponding to the at least one area comprises:
adjusting light-emitting luminance of display light source corresponding to an entire display area after scanning of the entire display area is completed.
Further, before adjusting light-emitting luminance of display light source corresponding to the at least one area, the method further comprises:
acquiring a luminance adjustment formula which is appropriate for making display luminance after scanning of the at least one area is completed maintain within the specified range;
the adjusting light-emitting luminance of display light source corresponding to the at least one area: adjusting light-emitting luminance of display light source corresponding to the at least one area according to an acquired luminance adjustment formula.
Further, the method further comprises:
determining a scanning period of time of the at least one area;
adjusting light-emitting luminance of display light source corresponding to the at least one area to a predetermined initial light-emitting luminance within a determined scanning period of time.
There is further provided according to a second aspect of the present disclosure a display driving apparatus, comprising:
a determining module, configured to determine whether scanning of at least one area of display areas is completed;
an adjusting module, configured to adjust light-emitting luminance of display light source corresponding to the at least one area after scanning of the at least one area is completed, such that display luminance of the at least one area maintains within a specified range.
Further, the display driving apparatus further comprises: a pulse width modulating module.
The adjusting module is configured to generate a control signal used to control the pulse width modulating module after scanning of the at least one area is completed;
The pulse width modulating module is configured to receive the control signal, perform pulse modulation according to the control signal, and adjust light-emitting luminance of display light source corresponding to the at least one area.
Further, the display area comprises a plurality of areas, each of which is corresponding to an independent group of display light sources;
The adjusting module is configured to adjust light-emitting luminance of display light source corresponding to each area sequentially in a scanning order of each area.
Further, the adjusting module is configured to adjust light-emitting luminance of display light source corresponding to an entire display area after scanning of the entire display area is completed.
Further, the display driving apparatus further comprises:
an acquiring module, configured to acquire a luminance adjustment formula which is appropriate for making display luminance after scanning of the at least one area is completed maintain within the specified range;
The adjusting module is configured to adjust light-emitting luminance of display light source corresponding to the at least one area according to an acquired luminance adjustment formula.
Further, the determining module is configured to determine a scanning period of time of the at least one area;
The adjusting module is further configured to adjust light-emitting luminance of display light source corresponding to the at least one area to a predetermined initial light-emitting luminance within the scanning period of time determining by the determining module.
There is provided according to a third aspect of the present disclosure a display device, comprising the display driving apparatus described above.
The backlight source driving method provided in some embodiments of the present disclosure is capable of reducing commendably the change of display luminance of the at least one area by adjusting the light-emitting luminance of display light source corresponding to the at least one area, so that picture flicker caused by over change of the display luminance would be avoided.
In order to make principles, technical solutions and advantages of embodiments of the present disclosure more clear, technical solutions in the embodiments of the present disclosure will be described clearly and completely by combining with accompanying figures. Obviously, embodiments described below are just a part of embodiments of the present disclosure, but not all the embodiments.
In step S1, determining whether scanning of at least one area of display areas is completed;
In step S2, adjusting light-emitting luminance of display light source corresponding to the at least one area after scanning of the at least one area is completed, such that display luminance of the at least one area maintains within a specified range.
The display driving method provided in the embodiments of the present disclosure is capable of reducing change of display luminance of the at least one area by adjusting the light-emitting luminance of display light source corresponding to the at least one area, so that picture flicker caused by excessive change of the display luminance would be avoided.
Alternatively, there could be many kinds of ways to implement step S1 in the above driving method of backlight source, for example, determining that scanning of the at least one area is completed according to a trigger signal produced by a gate driving circuit after scanning of the area is completed, or determining whether at least one area of display areas is completed or not according to a preset timer (for example, when the at least one area herein is an entire display area, one timer can be set when each frame starts. A length of the timer is a time length required for scanning the entire display area. Then, when timing of the timer is completed, it can be determined that scanning of this area is completed). How to specifically determine whether the scanning of one area is completed may be implemented through a variety of ways. Examples are not given one by one herein.
Upon specific implementation, the process of adjusting light-emitting luminance of display light source corresponding to the at least one area may continue until scanning of at least one area in a next frame starts, so that luminance maintains consistent before the at least one area is scanned in the next frame. Also, the process of adjusting may just continue to the time when the next frame starts, only to make the display luminance of the at least one area within the current frame maintain unchanged, or the process of adjusting may continue to other time nodes before scanning of the area in the next frame starts.
In specific implementation, the above method can further comprise steps not shown in
determining a scanning period of time of the at least one area; and
adjusting light-emitting luminance of display light source corresponding to at least one area to a predetermined initial light-emitting luminance within a determined scanning period of time.
Since it is very likely that the light-emitting luminance of the area may change when the at least one area is scanned (when displayed pictures change, display gray scales of a plurality of areas change), and degree of deflection of a corresponding liquid crystal is also reset, adjusting light-emitting luminance of display light source back to a predetermined initial light-emitting luminance within this period of time is capable of avoiding human eyes from feeling flicker of a same picture better than adjusting back within other periods of time.
It is easy to understand that, maintaining the display luminance within a specified range as described in the present disclosure means that in the area, amplitude of fluctuation of display luminance after completion of scanning relative to display luminance upon completion of scanning or at a certain moment in the process of scanning is smaller than a value which can make human eyes feel flicker. In specific implementation, the maximum value and minimum value of the above specified range can be set according to actual requirements only if the value satisfies a requirement of being capable of eliminating flicker of the display picture.
Exemplarily, adjusting light-emitting luminance of display light source corresponding to the at least one area can refer to adjusting dynamically the light-emitting luminance of display light source corresponding to the area according to a certain cycle after scanning of the at least one area is completed, so that the light-emitting luminance of display light source corresponding to the area compensates for the change of display luminance caused by factors such as decrease of pixel voltage within this area, so as to make the total display luminance maintain within a specified range.
The display driving method provided in the embodiment of the present disclosure can be used to drive backlight source of a liquid crystal display device in a normally black mode. Herein, as an example, adjusting light-emitting luminance of display light source corresponding to the at least one area can comprise: adjusting light-emitting luminance of display light source corresponding to the at least one area according to following luminance adjustment formula: Ct: Ct=C0*et/τ; where C0 is light-emitting luminance of display light source corresponding to the at least one area at an adjustment starting moment, t is time length between a current moment and the adjustment starting moment, and τ is a product of a pixel leakage resistance and a pixel capacitance. The pixel leakage resistance herein can in particular refer to resistance on a loss path with charges of pixel electrodes. In particular, it may refer to equivalent resistance of all materials causing leakage of the pixel electrodes and contacting with the pixel electrodes, such as source and drains of thin film transistors, liquid crystal layers, etc. In specific implementation, the specific value of τ herein can be measured by experiment.
In the process of liquid crystal displaying, the rule that a pixel voltage Vt written into respective pixels changes frequently keeps to: Vt=e−t/τ*V0, where V0 is an initial voltage of the pixel voltage, that is, the pixel voltage Vt reduces gradually as time increases. Correspondingly, in a liquid crystal display device in the normally black mode, the rule that transmittance Tt changes with time also keeps to: Tt=a*e−t/τ, where a is a constant relevant to a liquid crystal display device to be driven, and can be measured by experiment. Thus it can be seen that the longer the time is, the greater the transmittance changes, which would result in an apparent flicker phenomenon in a conventional low-frequency driven display device. And as to the display luminance of the screen, Bt=C*Tt. In this way, the luminance C of the display light source can be adjusted correspondingly, and thus the display light source luminance C also changes with time, so that the display luminance Bt maintain stable. Then, in order to make Ct*Tt==B0, Ct=B0/Tt=C0*T0/Tt=C0*a/(a*e−t/τ)=C0*et/τ can be obtained, where B0 is display luminance at the moment of starting adjustment, such that the display luminance does not change with time substantially. In this way, the apparatus that executes the above display driving method can realize the corresponding adjusting process without performing complicated calculations.
Further, in a liquid crystal display apparatus in a normally white mode, the rule that respective pixel transmittance Tt changes with time keep to: Tt=a*et/τ. Correspondingly, the light-emitting luminance C of display light source can be adjusted correspondingly, and thus the light-emitting luminance C of the display light source also changes with time, so that the display luminance Bt keeps stable. In order to make that Ct*Tt==B0, Ct=B0/Tt=C0*T0/Tt=C0*a/(a*et/τ)=C0*e−t/τ can be obtained. In the liquid crystal display device in the normally white mode, adjusting of light-emitting luminance of display light source corresponding to the at least one area can include: adjusting light-emitting luminance Ct, of display light source corresponding to the at least one area according to following luminance adjustment formula:
Ct:Ct=C0*e−t/τ.
In a specific implementation, the above display area can comprise a plurality of areas, each of which is corresponding to an independent group of display light sources.
At this time, in the above driving method, the step S2 can refer to:
adjusting sequentially light-emitting luminance of display light source corresponding to each area in a scanning order of each area.
In specific implementation, the display area can be divided into a plurality of areas, each different display area is corresponding to a different display light source, each area is scanned separately, and after scanning of a first area is completed, display light source corresponding to the first area is adjusted; after scanning of a second area is completed, display light source corresponding to the second area is adjusted, adjusting of display light source corresponding to each area is performed after scanning of the area is completed, which reduces change of display luminance of the entire display area to the better.
In this way, it is capable of timely starting the process of adjusting the light-emitting unit of the row after scanning of one area corresponding to each row of display light source 400 is completed, so as to stabilize the display luminance of the area timely. Compared with the mode of adjusting luminance after the scanning of display images of the entire display area is completed, it is capable of further reducing change of display luminance of a display area scanned previously, so as to avoid picture flicker to the better.
Of course, in actual application, the aforementioned at least one area can be the entire display area. Then, the step S2 can be: adjusting light-emitting luminance of display light source corresponding to the entire display area after the scanning of the entire display area is completed.
Such mode is capable of having lower difficulty in controlling, and is convenient to design the apparatus for executing the above method.
Alternatively, in the step S2, the light-emitting luminance of the display light source corresponding to the at least one area can be adjusted by adopting the pulse width modulation mode. In particular, the light-emitting current of the display light source of the area can be adjusted dynamically by adopting the pulse width modulation mode, so as to adjust the light-emitting luminance of the display light source of the corresponding area. The pulse width modulation mode herein mainly refers to a mode of modulating by adjusting a duty ratio of the pulse within each cycle. Within each cycle, the greater the pulse width is, the larger the duty ratio of the pulse is, and then the average value of the current within the corresponding cycle is higher, so that the light-emitting luminance becomes larger.
For example, referring to
In specific implementation, in the above method, prior to the step S2, the method can further comprise:
acquiring a luminance adjustment formula which is appropriate for making the display luminance, after scanning of the at least one area is completed, maintain within the specified range;
At this time, the step S2 can comprise: adjusting light-emitting luminance of display light source corresponding to the at least one area according to an acquired luminance adjustment formula.
Exemplarily, the mode of acquiring the luminance adjustment formula can be a mode of receiving the luminance adjustment formula imported artificially. For example, production staff can determine the parameter ti in the formula of Ct=C0*e−t/τ by means of experimental statistics, and then the corresponding calculation formula is imported to the apparatus that executes the above driving method.
There is further provided in another embodiment of the present disclosure a display driving apparatus, which can be used to execute the display driving method described above. The apparatus comprises:
a determining module, configured to determine whether scanning of at least one area of display areas is completed;
an adjusting module, configured to adjust light-emitting luminance of display light source corresponding to the at least one area after scanning of the at least one area is completed, such that display luminance of the at least one area maintains within a specified range.
The display driving apparatus provided in the embodiment of the present disclosure is capable of reducing change of display luminance of the at least one area by adjusting the light-emitting luminance of display light source corresponding to the at least one area, so that picture flicker caused by over change of the display luminance would be avoided.
Further, the display driving apparatus further comprises:
a pulse width modulating module;
the adjusting module is configured to generate a control signal used to control the pulse width modulating module after scanning of the at least one area is completed.
The pulse width modulating module is configured to receive the control signal, and perform pulse modulation according to the control signal so as to adjust light-emitting luminance of display light source corresponding to the at least one area.
In specific implementation, the determining module and the adjusting module can be realized by a programmable logic controller, while the pulse width modulation module herein can be realized by a pulse width modulation circuit. Under the condition of being capable of realizing the present disclosure, adopting what kind of form to implement the above respective functional modules specifically is not limited, the corresponding technical solution shall fall into the protection scope of the present disclosure.
Further, the display area comprises a plurality of areas, each of which is corresponding to an independent group of display light sources.
The adjusting module is configured to sequentially adjust light-emitting luminance of display light source corresponding to each area according to a scanning order of each area.
Further, the adjusting module is configured to adjust light-emitting luminance of display light source corresponding to an entire display area after scanning of the entire display area is completed.
Further, the display driving apparatus further comprises:
an acquiring module, configured to acquire a luminance adjustment formula which is appropriate for making the display luminance after scanning of the at least one area is completed maintain within the specified range; and
the adjusting module is configured to adjust light-emitting luminance of display light source corresponding to the at least one area according to an acquired luminance adjustment formula.
Further, the determining module is configured to determine a scanning period of time of the at least one area; and
the adjusting module is further configured to adjust light-emitting luminance of display light source corresponding to the at least one area to a predetermined initial light-emitting luminance within the scanning period of time determined by the determining module.
In another embodiment of the present disclosure, there is further provided a display device comprising the display driving apparatus described above.
The display device herein can be any product or elements having the display function, such as an electronic paper, a mobile phone, a tablet computer, a television set, a display, a notebook computer, a digital photo frame, and a navigator, etc.
The above descriptions are just specific implementations of the present disclosure. However, the protection scope of the present disclosure is not limited thereto. Any alternation or replacement that can be conceived by those skilled in the art who are familiar with the technical field shall be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subjected to the protection scope of the claims.
The present application claims the priority of a Chinese patent application No. 201510626973.0 filed on Sep. 28, 2015. Herein, the content disclosed by the Chinese patent application is incorporated in full by reference as a part of the present disclosure.
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