TWI393105B - Liquid crystal display device and method of driving backlight module thereof - Google Patents

Description

Liquid crystal display device and driving method thereof

The invention relates to a liquid crystal display device and a driving method thereof.

With the advancement of flat display technology, thin display devices, such as liquid crystal televisions, and liquid crystal screens, have gradually entered people's daily lives. Due to factors such as improved image quality and lower prices, more and more consumers are choosing liquid crystal displays as display devices for personal computers. In response to the various requirements of consumers, the industry has been striving to develop liquid crystal displays with wider viewing angles, wider color gamuts and shorter response times.

The reaction time refers to the reaction speed of the liquid crystal display to the input signal, that is, the reaction time when the liquid crystal is turned from dark to bright or from bright to dark. With the development of technology, the reaction time of liquid crystal displays has been gradually reduced from the previous 20 milliseconds to 10 milliseconds. Recently, there have been liquid crystal displays with a reaction time of less than 5 milliseconds. In general, the length of response time of a liquid crystal display is one of the important factors that affect the clarity of a dynamic picture display. When the reaction time is not short enough, the user can easily see the phenomenon of residual image during the movement of the object in the picture. This phenomenon will seriously affect the quality of the picture and the comfort of the human eye when viewing the picture, and use it for a long time. More burden on the eyes.

Since the liquid crystal display continuously and stably displays the image, the image which is affected by the persistence of the human eye, even if the reaction time reaches theoretically 0 milliseconds, the image of the previous picture is inevitably visually generated. Thus, the conventional method of continuously reducing the liquid crystal reaction time is still limited to a certain extent to improve the effect of image sticking. Therefore, in order to further effectively improve the problem of visually generating image sticking, the industry has proposed a scanning backlight technology, which uses a backlight to alternately flash, so that the picture is approximated by "progressive scanning". Further, the display effect of a cathode ray tube (CRT) display is achieved. However, this method is difficult to be favored by the market because the life of the backlight tube is greatly shortened, and the complexity of the light source driving circuit and the production cost are increased.

Therefore, the industry has recently developed a Black Frame Insertion (BFI) technology, which periodically inserts low grayscale or black images between dynamic images to reduce image persistence and cause image sticking. happened. This method does not need to change the design of the backlight module, and can effectively improve the dynamic picture display quality of the liquid crystal display. However, the use of a black insertion technique that inserts a low gray scale or a full black image reduces the brightness of the screen display, and the deviation of the gray scale causes a change in the color temperature. When the liquid crystal display device is switched from the normal display mode to the display mode of the application black insertion technology, or when the display mode of the application black insertion technology is switched to the general display mode, the user obviously perceives the change of the picture brightness and the color temperature. It will greatly affect the display quality of the liquid crystal display device and the comfort of the user viewing the screen.

The present invention provides a liquid crystal display device and a driving method thereof for driving a backlight module, which are driven in different manners in different display modes to compensate for changes in display color temperature and display brightness of different display modes, thereby improving user's Visual comfort.

The invention provides a driving method of a backlight module of a liquid crystal display device. When the liquid crystal display device is in the normal display mode, the at least one first light source is driven to enable the backlight module to provide the first backlight to the display panel of the liquid crystal display device. When the liquid crystal display device is switched to the black insertion display mode, the first light source and the at least one second light source are simultaneously driven to enable the backlight module to provide a hybrid backlight to the display panel. The color temperature and brightness of the hybrid backlight are different from the color temperature and brightness of the first backlight, so that the display color temperature and the display brightness of the liquid crystal display device in the black insertion display mode are substantially the same as the display color temperature and display of the liquid crystal display device in the normal display mode. brightness.

The invention further provides a liquid crystal display device comprising a display panel and a backlight module. The backlight module is disposed on one side of the display panel and includes a first light source, a second light source, and a driving circuit. The light generated by the first light source and the second light source has different color temperatures. The driving circuit is used to drive at least the first light source. When the liquid crystal display device is switched to the black insertion display mode, the driving circuit is configured to simultaneously drive the first light source and the second light source to compensate for the display color temperature change and the display brightness change of the liquid crystal display device.

The above described objects, features, and advantages of the present invention will become more apparent and understood.

According to a preferred embodiment of the liquid crystal display device and the driving method thereof, when the liquid crystal display device is in the normal display mode, at least one first light source is driven, and when the liquid crystal display device is switched to a black insertion display mode, the liquid crystal display device is simultaneously driven. The first light source and the at least one second light source. The first light source and the second light source have different color temperatures, so that the backlight module provides backlights of different color temperatures and brightness to the display panel in different display modes, so that the liquid crystal display device has the essence in the normal display mode and the black insertion display mode. The same display color temperature and display brightness.

The preferred embodiments are set forth below as a detailed description of the invention, and are not intended to limit the scope of the invention. Furthermore, the drawings corresponding to the embodiments also omit unnecessary elements to clearly show the technical features of the present invention.

Referring to FIG. 1 and FIG. 2 together, FIG. 1 is a perspective exploded view of a liquid crystal display device according to a preferred embodiment of the present invention; and FIG. 2 is a schematic view of the backlight module of FIG. The liquid crystal display device 100 includes a display panel 10 and a backlight module 20. The backlight module 20 is disposed in parallel with the display panel 10 . In the embodiment, the backlight module 20 is disposed under the display panel 10 , and the backlight module 20 includes a first light source 21 and a second light source 22 . Drive circuit 25. In a preferred embodiment, the backlight module 20 can further include an optical sheet 26.

When the liquid crystal display device 100 is switched to the black insertion display mode, the drive circuit 25 is configured to simultaneously drive the first light source 21 and the second light source 22. Since the light generated by the first light source 21 and the second light source 22 has different color temperatures, the first light source 21 and the second light source 22 can be changed when the first light source 21 and the second light source 22 are simultaneously driven. The backlight module 20 provides the color temperature and brightness of the backlight of the display panel 100 to compensate for the display color temperature change and the display brightness change of the liquid crystal display device 100 in different display modes.

Next, please refer to FIG. 3 to FIG. 4B at the same time. The driving method of the backlight module 20 of the present embodiment will be described in detail below. 3 is a flow chart of a preferred embodiment of a driving method of a backlight module according to the present invention; FIGS. 4A and 4B are respectively a schematic view of the backlight module of FIG. 3 in a normal display mode and a black insertion display mode; .

When the liquid crystal display device 100 is in the normal display mode, the embodiment includes driving at least one first light source 21 (step S1).

As shown in FIG. 4A , in the normal display mode, the backlight module 20 drives the plurality of first light sources 21 by the driving circuit 25 to enable the backlight module 20 to provide the first backlight to the display panel 10 . Then, when the user manually performs the display mode switching of the liquid crystal display device 100, or the liquid crystal display device 100 receives the switching signal sent by the computer system, so that the liquid crystal display device 100 switches to the black insertion display mode, the embodiment is simultaneously driven. The first light source 21 and the at least one second light source 22 (step S2).

As shown in FIG. 4B, when the black display mode is inserted, the backlight module 20 simultaneously drives the plurality of first light sources 21 and the plurality of second light sources 22 by the driving circuit 25, so that the backlight module 20 provides the hybrid backlight to The display panel 10 is displayed. That is, the second light sources 22 are activated only when the liquid crystal display device 100 is switched to the black insertion display mode, and the plurality of first light sources are continuously driven by the driving circuit 25 before the liquid crystal display device 100 is switched to the black insertion display mode. 21 (step S1). In this embodiment, the color temperature of the second light source 22 is preferably lower than the color temperature of the first light source, such that the color temperature of the hybrid backlight is lower than the color temperature of the first backlight. In addition, since the driving circuit is in the black insertion display mode, the first light source 21 and the second light source 22 are simultaneously driven, so that the brightness of the hybrid backlight is higher than the brightness of the first backlight.

In this embodiment, the normal display mode is a general display mode without application black insertion technology. When the liquid crystal display device 100 is switched from the normal display mode to the black insertion display mode, a low color scale or even a black display screen is inserted between the general data screens, so that the user can view the display color temperature of the liquid crystal display device 100. Raise, and the display brightness will decrease. The backlight module 20 provides a mixed backlight when the color temperature is lower than the normal display mode when the black display mode is inserted, thereby compensating for the display color temperature of the liquid crystal display device 100 in the black insertion display mode, and using the provided brightness to be higher than the normal display mode. The backlight is mixed to compensate for the decrease in display brightness of the liquid crystal display device 100 in the black insertion display mode. By compensating the liquid crystal display device 100 in the black insertion display mode by mixing the backlight, the compensated display color temperature and display brightness can be substantially the same as the display color temperature and display brightness in the normal display mode. Therefore, the liquid crystal display device 100 does not perceive changes in the display color temperature and display brightness before and after the display mode is switched, and maintains visual comfort.

When the user manually performs the display mode switching of the liquid crystal display device 100, or the liquid crystal display device 100 receives the switching signal sent by the computer system, so that the liquid crystal display device 100 switches back to the normal display mode, the backlight module 20 turns off the second mode. The light source 22, that is, the backlight module 20, returns to the state in which the driving circuit 25 drives only the first light source 21 (as shown in step S1). When the liquid crystal display device 100 is not switched back to the normal display mode, the plurality of first light sources 21 and the plurality of second light sources 22 are simultaneously driven by the drive circuit 25. In other words, the liquid crystal display device 100 can achieve the effect of compensating the display color temperature and the display brightness by merely turning on or off the second light source 22 when the display mode is switched.

In a preferred embodiment of the method for driving the liquid crystal display device 100 and the backlight module 20 thereof, the backlight module 20 includes a plurality of first light sources 21 and a plurality of second light sources 22. In addition, in the above step S2, the driving circuit 25 can drive the same or different numbers of the first light source 21 and the second light source 22. The backlight module 20 can change the number of driving the first light source 21 and the second light source 22 according to requirements, and adjust the color temperature difference and the brightness difference between the first backlight and the hybrid backlight. For example, increasing the number of driving the second light sources 22 when inserting the black display mode causes the color temperature of the hybrid backlight to approach the color temperature of the second light source 22; and reducing the number of driving the second light sources 22 when the black display mode is inserted, The color temperature of the mixed backlight is brought closer to the color temperature of the first light source 21. In this way, when the grayscale of the low grayscale picture of the black insertion mode is lowered, or the number of black screens is increased (to further reduce the image sticking), the display between the normal display mode and the black insertion mode is displayed. When the difference between the color temperature and the display brightness is increased, the backlight module 20 can compensate by adjusting the number of the second light sources 22, and maintain the consistency of the display color temperature and the display brightness before and after the display mode switching of the liquid crystal display device 100.

As described above, the backlight module 20 of the present embodiment may include an optical film 26, such as a diffusion plate, which is preferably disposed above the first light source 21 and the second light source 22, and is located here. The light sources 21 , 22 and the display panel 10 are used to homogenize the light generated by the first light source 21 and the second light source 22 , so that the backlight module 20 can provide a uniform backlight to the display panel 10 . Further, the first light source 21 and the second light source 22 (for example, Cold Cathode Fluorescent Lamps (CCFLs), respectively, are arranged in a staggered manner. In other embodiments, the first light source 21 and the second light source 22 may also be Light Emitting Diodes (LEDs), respectively, or other backlight source types used in conventional liquid crystal display devices.

In the embodiment, the direct-lit backlight module 20 is taken as an example. The backlight module 20 includes a plurality of first light sources 21 and a plurality of second light sources 22, as shown in FIG. However, the backlight module 20 can also be an edge-lit backlight module and includes only one first light source 21 and one second light source 22.

Referring to FIG. 5, an exploded perspective view of a liquid crystal display device when the first light source and the second light source are lateral light sources are illustrated according to a preferred embodiment of the present invention. The liquid crystal display device 100' includes a liquid crystal display panel 10 and a backlight module 20'. The backlight module 20' is an edge-lit backlight module 20', and includes a first light source 21', a second light source 22', an optical film 26, a light guide plate 28, and a back plate 29. The liquid crystal display device 100' drives only the first light source 21' in the normal display mode, and simultaneously drives the first light source 21' and the second light source 22' when the liquid crystal display device 100' is switched to the black insertion display mode. By simultaneously driving the first light source 21' and the second light source 22' when the black display mode is inserted, a hybrid backlight with a lower color temperature and a higher brightness is generated, so that the liquid crystal display device 100' of the application side backlight type backlight module 20' is After switching to the black display mode, the color temperature and display brightness can still be displayed.

According to a preferred embodiment of the liquid crystal display device and the driving method thereof, the first light source is driven by the driving circuit in the normal display mode, and the first light source is simultaneously driven by the driving circuit when switching to the black insertion display mode. The second light source, wherein the color temperature of the second light source is lower than the color temperature of the first light source, thereby compensating for brightness loss and color temperature change when the liquid crystal display device switches to the black insertion display mode. Therefore, the liquid crystal display device can maintain the same color temperature and display brightness before and after switching to the black insertion display mode, which increases the visual comfort of the user and improves the overall quality of the product. Furthermore, the driving method disclosed in the present invention can also be applied to a conventional liquid crystal display device without significantly changing the structure and circuit design, and without greatly increasing the cost.

While the present invention has been described above by way of example, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. Other different embodiments are contemplated, and the scope of the present invention is defined by the scope of the appended claims.

10. . . Display panel

20, 20’. . . Backlight module

21, 21’. . . First light source

22, 22’. . . Second light source

25. . . Drive circuit

26. . . Optical diaphragm

28. . . Light guide

29. . . Backplane

100, 100’. . . Liquid crystal display device

1 is an exploded perspective view of a preferred embodiment of a liquid crystal display device of the present invention.

Figure 2 is a schematic view of the backlight module of Figure 1.

FIG. 3 is a flow chart of a preferred embodiment of a driving method of a backlight module of the present invention.

FIG. 4A is a schematic diagram showing the backlight module of FIG. 3 in a normal display mode.

FIG. 4B is a schematic diagram showing the backlight module of FIG. 3 in a black insertion display mode.

Figure 5 is a perspective exploded view of a liquid crystal display device in which a first light source and a second light source are lateral light sources according to a preferred embodiment of the present invention.

Claims (13)

A driving method of a backlight module of a liquid crystal display device, comprising: driving a first light source when the liquid crystal display device is in a normal display mode, so that the backlight module provides a first backlight to one of the liquid crystal display devices a display panel; and when the liquid crystal display device is switched to a Black Frame Insertion (BFI) display mode, simultaneously driving the first light source and a second light source to enable the backlight module to provide a hybrid backlight to the display a panel; wherein the color temperature and brightness of the hybrid backlight are different from the color temperature and brightness of the first backlight to compensate for a display color temperature change and a display brightness change of one of the liquid crystal display devices. The driving method of claim 1, wherein in the step of simultaneously driving the first light source and the second light source, the color temperature of the light generated by the first light source is substantially higher than the light generated by the second light source. The color temperature. The driving method of claim 2, wherein in the step of simultaneously driving the first light source and the second light source, a color temperature of the first backlight is substantially higher than a color temperature of the hybrid backlight. The driving method of claim 1, wherein in the step of simultaneously driving the first light source and the second light source, the brightness of the hybrid backlight is substantially greater than the brightness of the first backlight. A liquid crystal display device includes: a display panel; and a backlight module disposed on one side of the display panel, and comprising: a first light source, a second light source, the light generated by the first light source and the second light source have different color temperatures; and a driving circuit electrically connected to the first light source and the second light source; When the liquid crystal display device is switched to a black insertion display mode, the driving circuit is configured to simultaneously drive the first light source and the second light source to compensate for a display color temperature change and a display brightness change of one of the liquid crystal display devices. The liquid crystal display device of claim 5, wherein the color temperature of the light generated by the first light source is substantially higher than the color temperature of the light generated by the second light source. The liquid crystal display device of claim 5, wherein when the driving circuit drives only the first light source, the backlight module provides a first backlight to the display panel, and when the driving circuit simultaneously drives the first When a light source and the second light source are used, the backlight module provides a hybrid backlight to the display panel. The liquid crystal display device of claim 7, wherein the color temperature of the first backlight is substantially higher than the color temperature of the hybrid backlight. The liquid crystal display device of claim 7, wherein the brightness of the hybrid backlight is substantially greater than the brightness of the first backlight. The liquid crystal display device of claim 5, wherein the backlight module further comprises: a diffusion plate for homogenizing the light generated by the first light source and the second light source. The liquid crystal display device of claim 5, wherein the first light source comprises at least one cold cathode lamp or at least one light emitting diode. The liquid crystal display device of claim 5, wherein the second light source comprises at least one cold cathode lamp or at least one light emitting diode. The liquid crystal display device of claim 5, wherein the backlight module comprises a plurality of first light sources and a plurality of second light sources, wherein the first light sources and the second light sources are staggered.