TWI457908B - A method for improving image sticking of lcd and a lcd using the same - Google Patents

Description

Method for reducing image sticking of liquid crystal display and liquid crystal display using same

The present invention relates to the technology of liquid crystal displays, and more particularly to a method of reducing image sticking of a liquid crystal display and a liquid crystal display using the same.

A conventional liquid crystal display (LCD) drives a liquid crystal of the same pixel in a display panel in a fixed liquid crystal polarity driving sequence when displaying a screen. However, such a method will cause the liquid crystal display to continuously apply a DC bias voltage to the liquid crystal display for a long time, thereby causing the image to be branded, that is, the so-called afterimage (Image Sticking). As a result, the quality of the picture is greatly affected.

The present invention provides a method of reducing image sticking of a liquid crystal display.

The present invention further provides a liquid crystal display using the above method.

The invention provides a method for reducing the image sticking of a liquid crystal display, the method comprising the steps of: driving the liquid crystal display to switch the driving order of the liquid crystal polarity every predetermined time; and after the liquid crystal display switches the driving order of the liquid crystal polarity During the first frame time, reduce the brightness of one of the backlight modules of the liquid crystal display.

The invention further provides a liquid crystal display comprising a display panel, a scan driver, a data driver, a timing controller and a control circuit. The scan driver and the data driver are electrically connected to the display panel. The timing controller is electrically connected to the scan driver and the data driver for controlling the scan driver to scan the display panel and controlling the data driver to drive the display panel for display. The control circuit is electrically connected to the data driver, the timing controller and a backlight module. The control circuit controls the driving sequence of the liquid crystal polarity of the data drive switching display panel every other preset time, and controls the backlight in the first frame time after the data driver switches the driving order of the liquid crystal polarity of the display panel. The module reduces its brightness.

In summary, the present invention is a driving sequence in which the liquid crystal display switches the polarity of the liquid crystal every other preset time during the display of the liquid crystal display, and the first step after the liquid crystal display switches the driving order of the liquid crystal polarity. During the frame time, the brightness of one of the backlight modules of the liquid crystal display is lowered. Therefore, the liquid crystal of the same pixel will not be continuously applied with a DC bias, making it difficult for the display image to appear again. In other words, a liquid crystal display using this method will not easily exhibit image sticking. However, since the brightness of the backlight module of one of the liquid crystal displays is reduced in the first frame of the liquid crystal display after the liquid crystal display switches the driving order of the liquid crystal polarity, the brightness of the screen can be maintained. As a result, the quality of the picture is greatly improved.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

1 is a liquid crystal display according to an embodiment of the present invention. Referring to FIG. 1 , the liquid crystal display 100 includes a display panel 110 , a scan driver 120 , a data driver 130 , a timing controller 140 , a control circuit 150 , and a backlight module 160 . The display panel 110 has a plurality of pixels 112, and each of the pixels 112 has a liquid crystal molecule layer. Further, the display panel 110 is a common DC potential. The scan driver 120 and the data driver 130 are electrically connected to the display panel 110. The timing controller 140 is electrically connected to the scan driver 120 and the data driver 130 for controlling the scan driver 120 to scan the display panel 110 and controlling the data driver 130 to drive the display panel 110 for display.

As for the control circuit 150, the data driver 130, the timing controller 140 and the backlight module 160 are electrically connected, and the control circuit 150 controls the data driver 130 to switch the driving of the liquid crystal polarity of the display panel 110 every predetermined time. The sequence is illustrated in Figure 2.

Fig. 2 is a view showing an embodiment of the switching liquid crystal polarity driving sequence of the present invention. The switching mode shown in this figure is exemplified by the polarity of the liquid crystal under a different frame 112 of a certain pixel 112 in the display panel 110. As shown in FIG. 2, during the first frame to the Nth frame, the control circuit 150 controls the data driver 130 to drive the liquid crystal of the pixel 112 in the liquid crystal polarity driving sequence of positive and negative. Next, during the period from the N+1th frame to the Mth frame, the control circuit 150 controls the data driver 130 to drive the liquid crystal of the pixel 112 in the liquid crystal polarity driving sequence of negative and positive. Then, during the period from the M+1th frame to the Kth frame, the control circuit 150 controls the data driver 130 to drive the liquid crystal of the pixel 112 in the liquid crystal polarity driving sequence of positive and negative. Next, starting from the K+1th frame, the control circuit 150 controls the data driver 130 to drive the liquid crystal of the pixel 112 in the liquid crystal polarity driving sequence of negative and positive. The above N, M and K are all natural numbers, and K>M>N.

Briefly, the control circuit 150 controls the data driver 130 to switch the driving order of the liquid crystal polarity of the pixel 112 every predetermined time period to prevent the liquid crystal of the pixel 112 from being continuously positive and negative. The driving sequence is driven to prevent the liquid crystal of the pixel 112 from being continuously applied with a DC bias to create an imprint on the screen.

The preset time described above can be designed according to the tolerance of the customer or the display manufacturer itself for image sticking, as long as the interval of switching the liquid crystal polarity driving sequence is within a preset time. Taking FIG. 2 as an example, the length of the first frame to the Nth frame should not be greater than the preset time, and the length of the N+1th frame to the Mth frame should not be greater than the preset time. The length of the M+1th frame to the Kth frame should not be greater than the preset time. Further, as described above, since the interval of switching of the liquid crystal polarity driving order is within a preset time, the interval of the polarity switching may be fixed or non-fixed.

Referring to FIG. 2 again, since the liquid crystal of the pixel 112 is driven by the same polarity in the Nth frame and the N+1th frame, the pixel 112 will be in the N+1th frame. Brighter. Similarly, the pixel 112 is also brighter in the M+1th frame and the K+1th frame. That is to say, the pixel 112 will appear brighter during the time of switching the first frame after the liquid crystal polarity driving sequence of the pixel 112. Therefore, the control circuit 150 also controls the backlight module 160 to reduce the brightness of the first frame after the data driver 130 switches the driving order of the liquid crystal polarity of the display panel 110 to maintain the brightness of the screen. Taking FIG. 2 as an example, in the N+1th frame, the M+1th frame, and the K+1th frame, the control circuit 150 controls the backlight module 160 to reduce its brightness.

Please refer to Figure 1 again. In this example, the scan driver 120 receives the initial scan signal Ydio outputted by the timing controller 140, and outputs a plurality of scan pulses required to display a frame according to the start scan signal Ydio. The data driver 130 receives the data signal DS1 outputted by the timing controller 140, for example, receives the data signal DS1 in the form of a Mini Low Voltage Differential Signaling (mini-LVDS) format, and drives the display panel according to the data signal DS1. 110 for display.

The control circuit 150 is configured to receive the initial scan signal Ydio, the first liquid crystal polarity flip signal POL1 and the first duty cycle control signal BL_Duty1 output by the timing controller 140. When the data driver 130 needs to reverse the polarity of the liquid crystal of the display panel 110 according to the first liquid crystal polarity driving sequence, the control circuit 150 transmits the first liquid crystal polarity inversion signal POL1 and the first duty cycle control signal BL_Duty1 to the data driver 130 and the The backlight module 160 is configured to invert the polarity of the liquid crystal of the display panel 110 according to the first liquid crystal polarity flip signal POL1, and the backlight module 160 can operate according to the first duty cycle control signal BL_Duty1 to display the first brightness. .

When the data driver 130 needs to reverse the polarity of the liquid crystal of the display panel 110 according to the second liquid crystal polarity driving sequence, and the backlight module 160 needs to reduce its brightness, the control circuit 150 can reduce the duty cycle of the backlight module 160. Its brightness. For example, the control circuit 150 can generate the second liquid crystal polarity flip signal POL2 and the second duty cycle control signal BL_Duty2 with a smaller duty cycle according to the first liquid crystal polarity flip signal POL1 and the first duty cycle control signal BL_Duty1, respectively, and transmit the second duty cycle control signal BL_Duty2. The data driver 130 and the backlight module 160 are provided so that the data driver 130 reverses the polarity of the liquid crystal of the display panel 110 according to the second liquid crystal polarity flip signal POL2, and the backlight module 160 can operate according to the second duty cycle control signal BL_Duty2. And the second brightness is darker.

In addition, the control circuit 150 may count the preset time by using at least one of the first liquid crystal polarity flip signal POL1 and the initial scan signal Ydio. Of course, the control circuit 150 may use other methods or other signals to count the preset time, as long as the signal used is one of the signals output by the timing controller 140. It is worth mentioning that in this example, the data driver 130 may reverse the polarity of the liquid crystal in a dot inversion manner, which is not intended to limit the present invention. In addition, the control circuit 150 can be implemented by using a Complex Programmable Logic Device (CPLD).

3 illustrates a liquid crystal display in accordance with another embodiment of the present invention. In FIG. 3, the same reference numerals as those in FIG. 1 are indicated as the same object or signal. 3 is different from the two liquid crystal displays shown in FIG. 1 in that the liquid crystal display shown in FIG. 3 does not have a backlight module, and the timing controller 140 in the liquid crystal display is electrically connected to the control circuit 150. To the test module 170 provided by the client. In addition, the timing controller 140 also does not provide the first duty cycle control signal BL_Duty1 to the control circuit 150. The test module 170 includes a system circuit 172 and a backlight module 174. The system circuit 172 is configured to provide the data signal DS2 of another format to the timing controller 140, for example, to provide the data signal DS2 of the low-voltage differential signal format to the timing controller 140, so that the timing controller 140 formats the data signal DS2. Obtain the data signal DS1. In addition, the system circuit 172 is further configured to provide a first duty cycle control signal BL_Duty1 to the control circuit 150. The backlight module 174 is configured to operate according to the first duty cycle control signal BL_Duty1 or the second duty cycle control signal BL_Duty2 transmitted by the control circuit 150 to present a corresponding brightness.

With the above teachings, those having ordinary skill in the art can summarize some basic steps of reducing the image sticking of the liquid crystal display of the present invention, as shown in FIG. Referring to FIG. 4, the method includes the following steps: driving the liquid crystal display to switch the driving order of the liquid crystal polarity every predetermined time (as shown in step S402); and first after the liquid crystal display switches the driving order of the liquid crystal polarity. During the time of the picture frame, the brightness of one of the backlight modules of the liquid crystal display is lowered (as shown in step S404).

In summary, the present invention is a driving sequence in which the liquid crystal display switches the polarity of the liquid crystal every other preset time during the display of the liquid crystal display, and the first step after the liquid crystal display switches the driving order of the liquid crystal polarity. During the frame time, the brightness of one of the backlight modules of the liquid crystal display is lowered. Therefore, the liquid crystal of the same pixel will not be continuously applied with a DC bias, making it difficult for the display image to appear again. In other words, a liquid crystal display using this method will not easily exhibit image sticking. However, since the brightness of the backlight module of one of the liquid crystal displays is reduced in the first frame of the liquid crystal display after the liquid crystal display switches the driving order of the liquid crystal polarity, the brightness of the screen can be maintained. As a result, the quality of the picture is greatly improved.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

100. . . LCD Monitor

110. . . Display panel

112. . . Pixel

120. . . Scan drive

130. . . Data driver

140. . . Timing controller

150. . . Control circuit

160. . . Backlight module

170. . . Test module

172. . . System circuit

174. . . Backlight module

BL_Duty1. . . First duty cycle control signal

BL_Duty2. . . Second duty cycle control signal

DS1, DS2. . . Data signal

POL1. . . First liquid crystal polarity flip signal

POL2. . . Second liquid crystal polarity flip signal

S402, S404. . . step

Ydio. . . Initial scan signal

1 is a liquid crystal display according to an embodiment of the present invention.

Fig. 2 is a view showing an embodiment of the switching liquid crystal polarity driving sequence of the present invention.

3 illustrates a liquid crystal display in accordance with another embodiment of the present invention.

4 is a flow chart of a method of reducing image sticking of a liquid crystal display according to an embodiment of the invention.

S402, S404. . . step

Claims (11)

A method for reducing image sticking of a liquid crystal display, comprising: driving a liquid crystal display to switch a liquid crystal polarity every other preset time; and a first frame after the liquid crystal display switches the driving order of the liquid crystal polarity The brightness of one of the backlight modules of the liquid crystal display is reduced. The method of claim 1, comprising reducing the brightness of the backlight module by reducing a duty cycle of the backlight module. The method of claim 1, comprising counting the preset time by using one of the signals output by a timing controller of the liquid crystal display. The method of claim 1, wherein the liquid crystal display reverses the polarity of the liquid crystal in a dot inversion manner. The method of claim 1, wherein the display panel of the liquid crystal display adopts a constant current common potential. A liquid crystal display comprising: a display panel; a scan driver electrically connected to the display panel; a data driver electrically connected to the display panel; and a timing controller electrically connected to the scan driver and the data driver for Controlling the scan driver to scan the display panel, and controlling the data driver to drive the display panel for display; and a control circuit electrically connecting the data driver, the timing controller and a backlight module, and every other preset The control circuit controls the driving sequence of the data driver to switch the polarity of the liquid crystal of the display panel, and controls the time in the first frame after the data driver switches the driving order of the liquid crystal polarity of the display panel. The backlight module reduces its brightness. The liquid crystal display of claim 6, wherein the control circuit is further configured to receive a first duty cycle control signal and a first liquid crystal polarity flip signal from the timing controller, and when the data driver is required to be When the first liquid crystal polarity driving sequence reverses the polarity of the liquid crystal of the display panel, the control circuit transmits the first liquid crystal polarity reversal signal and the first duty cycle control signal to the data driver and the backlight module, respectively. And when the data driver needs to reverse the polarity of the liquid crystal of the display panel according to a second liquid crystal polarity driving sequence, and the backlight module needs to reduce the brightness thereof, the control circuit converts the signal according to the first liquid crystal polarity and the first A duty cycle control signal generates a second liquid crystal polarity flip signal and a second duty cycle control signal, respectively, and is respectively transmitted to the data driver and the backlight module. The liquid crystal display of claim 7, wherein the first duty cycle control signal is from the timing controller or a system circuit. The liquid crystal display of claim 7, wherein the control circuit is further configured to receive a start scan signal from the timing controller, and to use the first liquid crystal polarity flip signal and the initial scan signal to at least One to count the preset time. The liquid crystal display of claim 6, wherein the data driver reverses the polarity of the liquid crystal in a dot inversion manner. The liquid crystal display of claim 6, wherein the display panel adopts a constant current common potential.