The embodiments of the invention relates to a liquid crystal display (LCD) driving method and a LCD driving device.
Thin film transistor liquid crystal displays (TFT-LCDs), mainstream products in the display market, are widely used in televisions and computer displays. A LCD panel is the main component of a TFT-LCD and comprises a color filter substrate, a TFT array substrate, liquid crystal, sealant, orientation films, and etc.
A LCD often has defects, such as tailing, slow response, and image sticking, among which image sticking has a significant adverse effect on display quality of the LCD.
Image sticking refers to the following phenomenon: after a TFT-LCD displays a first image, such as the black and white chessboard, as shown in
Image sticking has a significant adverse effect on the display quality of a TFT-LCD, and thus has been the research focus of TFT-LCD manufacturing companies. The conventional methods correct image sticking from four aspects, including: pixel design, array structure, material and processing for liquid crystal, and driving method. One important approach is to reduce the ion concentration in a LCD panel and thus correct image sticking via material selection for a TFT-LCD. Nevertheless, on one hand, the ion concentration in the material of liquid crystal and the orientation film is already very low, and thus it is difficult to further decrease the ion concentration from this point; on the other hand, because the material of liquid crystal is a mixture of liquid crystal of many sorts, it is hardly possible to analyze mutual impact among them, as well as the mutual impact between various components of the liquid crystal material and the orientation film or sealant, which renders it especially difficult to further correct image sticking via analysis.
In one respect, an embodiments of the invention provides a method of correcting image sticking in a liquid crystal display (LCD), comprising steps of: determining whether any change occurs to a first image displayed by refreshing on a LCD in a predetermined time period; and controlling the LCD to refresh to display, after the predetermined time period, a second image that is different from the first image, if it is determined that no change occurs to the first image displayed by refreshing on the LCD in the predetermined time period, so as to correct image sticking caused by displaying the first image for a long period of time.
In another respect, an embodiment of the invention provides a liquid crystal display (LCD) driving device, comprising: a gate electrode driving circuit; a source electrode driving circuit; a determining module, for determining, based on feeding information, whether any change occurs to a first image displayed by refreshing on a LCD in a predetermined time period; a control module, connected to the gate electrode driving circuit, the source electrode driving circuit, and the output end of the determining module, for controlling the LCD to refresh to display, after the predetermined time period, a second image that is different from the first image through operation of the gate electrode driving circuit and the source electrode driving circuit, if it is determined that no change occurs to the first image displayed by refreshing on the LCD in the predetermined time period, so as to correct image sticking caused by displaying the first image for a long period of time.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from the following detailed description.
The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein:
Hereinafter, detailed description of the embodiments will be given with references to the accompanying drawings.
Usually, the magnitude of RDCV (remaining direct current voltage) can be used to indicate the seriousness of image sticking; the larger the RDCV is, the more serious the image sticking is. Regarding the white squares shown in
The time period T1 is approximately 2000˜6000s, and the time period T2 is about 2˜30s. The increasing rate of RDCV in the period T1 is much smaller than the decreasing rate in the period T2. As can be seen from
For instance, for a LCD with a refreshing rate of 60 Hz, it is feasible to insert a particular image every one second. Take the familiar image sticking evaluation image shown in
Here, the reason for not straightly inserting a grey image of grey level 255 is that, in addition to reduce RDCV, having approximately equal RDCVs in black and white squares is also concerned. Regarding the black squares in
For another example,
The first embodiment of the invention provides a method of correcting image sticking of a LCD. The method comprises the following steps.
Step 401, determining whether any change occurs to a first image displayed by refreshing on a LCD in a predetermined time period.
Displaying each image on a LCD requires a given refreshing rate, and the refreshing rate can generally be 60 Hz for a LCD.
Step 402, controlling the LCD to refresh to display, after the predetermined time period, a second image that is different from the first image, if it is determined that no change occurs to the first image displayed by refreshing on the LCD in the predetermined time period, so as to reduce image sticking caused by displaying the first image for a long period of time.
In step 402, the sum of the grey level of each sub-pixel of the second image and that of the corresponding sub-pixel of the first image can be within the range of 250˜260, preferably equal to 255.
The method of correcting LCD image sticking according to the embodiment can reduce RDCV caused by displaying the first image for a long period of time and thus corrects image sticking in a LCD and improves image displaying quality of the LCD, by way of inserting a second image that is different from the first image after the first image has been displayed for a long period of time.
Step 501, setting a predetermined time period.
The predetermined time period can usually be set within the range of 0.5˜1.5 s; but it is not specifically limited, it can be any time during which image sticking occurs after displaying the same image for a long period of time. In this embodiment, the predetermined time period can be 59/60 s, and the corresponding image refreshing rate can be 60 Hz.
Step 502, storing the first image displayed by refreshing on the LCD in the predetermined time period.
Step 503, determining whether any change occurs to a first image displayed by refreshing on the LCD in the predetermined time period. If some change does occur, i.e., the displayed image is not the same one in the predetermined time period, it means the LCD did not display the same image for a long period of time and hence there will be almost no RDCV, the image to be displayed can be displayed regularly; otherwise step 504 is executed.
Step 504, calculating, after the predetermined time period, the grey level of each sub-pixel of the second image in accordance with the grey level of the corresponding sub-pixel of the first image.
In the step, during calculation of the grey level of each sub-pixel of the second image, the sum of the grey level of each sub-pixel of the second image and that of the corresponding sub-pixel of the first image can be preferably set as 255.
Step 505, controlling the LCD to refresh to display the second image in accordance with the grey level of each sub-pixel of the second image obtained through calculation, through voltage driving, with a refreshing rate identical to or different from that for displaying the first image. The second image can be refreshed to display once or more during displaying.
In step 505, the refreshing rate and time for the second image can be chosen by a selecting circuit, the refreshing rate of the second image can be different from that of the first image and the second image can be refreshed to display once or more, as long as the time of displaying the second image on the LCD is shorter than the shortest visual persistence time of human eyes. For example, in the case where the refreshing rate for the first image is set as 60 Hz, the predetermined time period can be set as 59/60 s, during which the first image will be displayed by refreshing for 59 times (here, for sake of convenience, loading the image is treated as the first time of refreshing) with a displaying interval of 1/60 s. The refreshing rate of the second image can be set identical to that of the first image, i.e., 60 Hz, and the second image can be refreshed once (i.e., loading the second image is treated as one refreshing for sake of convenience); in such a case, the second image is displayed for a period of 1/60 s, shorter than the shortest visual persistence time of human eyes (0.05 s˜0.2 s). The refreshing rate of the second image can also be set different from that of the first image, e.g., 100 Hz, and the second image can be refreshed twice; in such a case, the second image is displayed for a period of 0.02 s, still shorter than the shortest visual persistence time of human eyes (0.05 s˜0.2 s).
The method of correcting LCD image sticking according to this embodiment can reduce RDCV caused by displaying the first image for a long period of time and thus corrects image sticking in a LCD and improves image displaying quality of the LCD, by way of inserting a second image that is different from the first image after the first image has been displayed for a long period time.
The LCD driving device according to this embodiment can reduce RDCV caused by displaying the first image for a long period of time and thus corrects image sticking in a LCD and improves image displaying quality of the LCD, by way of inserting a second image that is different from the first image after the first image has been displayed for a long period of time.
An example of the determining module 23 can comprise: a setting sub-module 231, a storing sub-module 232, and a determining sub-module 233. The setting sub-module 231 is employed to set the predetermined time period; the storing sub-module 232, receiving feeding information and connected to the setting sub-module 231, is employed to store the first image displayed in the predetermined time period; the determining sub-module 233, connected to the storing sub-module 232, is employed to determine, based on the first image stored by the storing sub-module 232 and displayed in the predetermined time period, whether changes occur to the first image displayed by refreshing on the LCD in the predetermined time period.
An example of the control module 24 can comprise: a calculating sub-module 241 and a driving sub-module 242. The calculating sub-module 241 is employed to calculate, after the predetermined time period, the grey level of each sub-pixel of the second image in accordance with the grey level of each sub-pixel of the first image; the sum of the grey level of each sub-pixel of the second image and that of the corresponding sub-pixel of the first image is preferably 255. The driving sub-module 242 is employed to control the LCD to refresh to display the second image in accordance with the grey level of each sub-pixel of the second image calculated with the calculating sub-module 241, through voltage driving by the gate electrode driving circuit and the source electrode driving circuit, and with a refreshing rate equal to or different from that for refreshing to display the second image; the second image can be refreshed once or more. The time the LCD refreshes and displays the second image is shorter than the shortest visual persistence time of human eyes.
In addition, the control module 24 can further includes: a frequency selection sub-module 243, which, connected to the driving sub-module 242, is employed to transmit, after the predetermined time period, the refreshing rate for refreshing to display the second image to the driving sub-module 242.
The LCD driving device according to this embodiment can reduce RDCV caused by displaying the first image for a long period of time and thus corrects image sticking in a LCD and improves image displaying quality of the LCD, by way of inserting a second image that is different from the first image after the first image has been displayed for a long period of time.
Lastly, the aforementioned embodiments are employed to describe, not to limit, the invention. Notwithstanding that a detailed description is given with references to the embodiments as above, as one of ordinary skill in the art understands, the technique embodied in the above embodiments can be modified, or some technical features can be substituted with the equivalents; such modifications or substitutions do not deviate the nature of the technique from the spirit and scope of the technique embodied in the embodiments according to the invention.
Number | Date | Country | Kind |
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200910091910.4 | Aug 2009 | CN | national |