1. Field of the Invention
The present disclosure relates to a backlight control module and a backlight control method, and more particularly, to a backlight control module and a backlight control method capable of performing local dimming controls of at least one display area of a display device.
2. Description of the Prior Art
As a local dimming control technology becomes mature, more and more display devices (e.g., liquid-crystal display (LCD) monitors, LCD televisions, LED LCD monitors, LED LCD televisions, etc.) equip with the local dimming control technology, to reduce power consumption, decrease light leakage and increase dynamic contrast when the display devices do not need to be full bright or full dark. In detail, the local dimming control technology first divides a display device into multiple display areas and then adjusts a backlight of each display area according to brightness of an area frame of each display area. For example, a weaker backlight can be used for a display area with a darker area frame to reduce the power consumption and decrease the light leakage in the display area, and a stronger backlight can be used for a display area with a brighter area frame to represent image details more clearly to increase the dynamic contrast. Thus, a user can acquire better viewing experience though the local dimming control technology.
The present disclosure discloses a backlight control module, for generating at least one pulse-width modulation (PWM) signal to perform local dimming controls on at least one display area of a display device. The backlight control module includes a backlight computing unit, for configuring a frequency of the at least one PWM signal according to a frequency of a frame when at least one area frame of the at least one display area is used for displaying the frame; a timing control unit, for configuring at least one starting time instant of a period of the at least one PWM signal according to at least one starting time instant of the at least one area frame, respectively; and a PWM unit, coupled to the backlight computing unit and the timing control unit for generating the at least one PWM signal and configuring at least one width of at least one on-period of the period of the at least one PWM signal according to at least one image data of the at least one area frame, respectively, wherein the at least one on-period is located at an end of the period of the at least one PWM signal, respectively.
The present disclosure further discloses a backlight control method for generating at least one pulse-width modulation (PWM) signal to perform local dimming controls on at least one display area of a display device. The backlight control method includes configuring a frequency of the at least one PWM signal according to a frequency of a frame, when at least one area frame of the at least one display area is used for displaying the frame; configuring at least one starting timing instant of a period of the at least one PWM signal according to at least one starting time instant of the at least one area frame, respectively; and generating the at least one PWM signal and configuring at least one width of at least one on-period of the period of the at least one PWM signal according to at least one image data of the at least one area frame, respectively, wherein the at least one on-period is located at an end of the period of the at least one PWM signal, respectively.
The present disclosure further discloses a liquid-crystal display device, including a display panel, for displaying a frame; and a backlight control module, coupled to the display panel for generating at least one pulse-width modulation (PWM) signal to perform local dimming controls on at least one display area of the display panel, the backlight control module including: a backlight computing unit, for configuring a frequency of the at least one PWM according to a frequency of the frame, when at least one area frame of the at least one display area is used for displaying the frame; a timing control unit, for configuring at least one starting time instant of a period of the at least one PWM signal according to at least one starting time instant of the at least one area frame, respectively; and a PWM unit, coupled to the backlight computing unit and the timing control unit for generating the at least one PWM signal and configuring at least one width of at least one on-period of the period of the at least one PWM signal according to at least one image data of the at least one area frame, respectively, wherein the at least one on-period is located at an end of the period of the at least one PWM signal, respectively.
The present disclosure further discloses a backlight control module, for generating a first pulse-width modulation (PWM) signal and a second PWM signal to perform local dimming controls on a first display area and a second display area of a display device. The backlight control module includes a backlight computing unit, for configuring a frequency of the first PWM signal and a frequency of the second PWM signal according to a frequency of a frame when a first area frame of the first display area and a second area frame of the second display area are used for displaying parts of the frame; a timing control unit, for configuring a starting time instant of a period of the first PWM signal and a starting time instant of a period of the second PWM signal according to a starting time instant of the first area frame and a starting time instant of the second area frame, respectively; and a PWM unit, coupled to the backlight computing unit and the timing control unit for generating the first PWM signal and the second PWM signal and configuring a width of an on-period of the period of the first PWM signal and a width of an on-period of the period of the second PWM signal according to an image data of the first area frame and an image data of the second area frame, respectively, wherein the on-period of the first PWM signal and the on-period of the second PWM signal are located at an end of the period of the first PWM signal and an end of the period of the second PWM signal, respectively.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
Please refer to
Please refer to
In addition, the display device 20 is used for illustrating the concept of the present invention in the above description, those skilled in the art may accordingly observe appropriate alternations or modifications. For example, the display device includes a display panel for displaying the frame, generally. When the display device further includes the backlight control module of the present disclosure, the backlight control module can control the local dimming of the display panel via coupling the backlight control module of the present disclosure (e.g., the backlight control module 10) to the display panel. That is, the display area of the display device 20 can be substituted by a display area of the display panel of the display device 20. The operation methods can be known by referring to the above and are not narrated herein for brevity.
Please refer to
Taking the display area DA_21 as an example, when the starting time instant of the area frame FRM_21 is not considered, the starting time instant of the period of the PWM signal sig_21 can be the starting time instant t1 or an arbitrary time instant. When the display device 20 begins reading the frame according to the vertical synchronization signal Vsync, the area frames located on different display areas would have different starting time instants. For example, the different starting time instants may be caused by delays which are caused by different locations of the display areas. Thus, after the timing control unit 102 or other computing unit estimates or calculates that the starting time instant of the area frame FRM_21 is the time instant t2, the timing control unit 102 adjusts the starting time instant of the period of the PWM signal sig_21 to the time instant t2, accordingly, to completely synchronize (i.e., synchronize in the time and the frequency) the PWM signal sig_21 with the area frame FRM_21. Similarly, under the condition that the time instant t2, the time instant t3 and the time instant t4 are the starting time instants of the area frames FRM_22-FRM_24, the area frames FRM_31-FRM_34 and the area frames FRM_41-FRM_44, the timing control unit 102 can adjust the starting time instants of the periods of the PWM signals sig_22-sig_24, the PWM signals sig_31-sig_34 and the PWM signals sig_41-sig_44 to the time instants t2, the time instant t3 and the time instant t4, respectively. As a result, the PWM signals sig_22-sig_24, the PWM signals sig_31-sig_34 and the PWM signals sig_41-sig_44 are synchronized with the area frames FRM_22-FRM_24, the area frames FRM_31-FRM_34 and the area frames FRM_41-FRM_44, respectively.
Please note that, methods of determining the starting time instants of the area frames FRM_11-FRM_44 are not limited. For example, the starting time instants of the area frame FRM_11-FRM_44 can be determined according to starting times of transitions of liquid-crystal components of the display areas DA_11-DA_44, respectively. For example, in the display area DA_21, a set of liquid-crystal components may start transition after delaying a specific time (e.g., delaying (t2-t1) unit time) due to the position of the display area DA_21, to display the area frame FRM_21, when the display device 20 begins reading the frame according to the vertical synchronization signal Vsync. The timing control unit 102 can determine the starting time instant t2 of the area frame FRM_22 according to the starting time of the transition of the set of liquid-crystal components in the display area DA_21. For example, the set of the liquid-crystal components is the liquid-crystal components located on a horizontal scan line of the display area DA_21. Preferably, the horizontal scan line is located at a middle position of the display area DA_21, to reduce errors between the starting time instant t2 of the period of the PWM signal sig_21 and other scan lines of the display area DA_21. Noticeably, when the starting time instants of the area frame FRM_11-FRM_44 (e.g., the delays needed by liquid-crystal transitions) increase from top to bottom according to the positions of the display areas DA_11-DA_44 (e.g., when the display device 20 is a direct back-lit LED LCD display device), a better result can be obtained by determining the starting time instant of the display area according to the horizontal scan line located at the middle position of the display area. Similarly, the timing control unit 102 can determine the starting time instants t1-t4 according to the above principles which is not narrated herein for brevity. As a result, the motion blur caused by the differences between the starting time instants of the area frames can be reduced.
The PWM unit 104 also needs to decide the widths w11-w44 and positions of the on-period ON_11-ON_44 in addition to determining the starting time instants of the periods of the PWM signals sig_11-sig_44, when generating the PWM signals sig_11-sig_44. For example, the PWM unit 104 determines the width w21 of the on-period ON_21 of the PWM signal sig_21 according to a brightness level (e.g., a grey-level value) of image data of the area frame FRM_21. In one example, the PWM unit 104 determines that the width w21 of the on-period ON_21 is proportional to the grey-level value of the area frame FRM_21. That is, the width w21 is broader when the image data of the area frame FRM_21 has a higher grey-level value; and the width w21 is narrower when the image data of the area frame FRM_21 has a lower grey-level value. In addition, since the liquid-crystal needs a specific time to reach a steady state (i.e. finishing the transition) after starting the transition starts, the PWM unit 104 can configure the on-period ON_21 at an end of the period of the PWM signal sig_21 (i.e. configuring the off-period at a front end of the period) after determining the width w21 of the on-period ON_21, to maximize an overlapped part between the on-period ON_21 and the period where the liquid-crystal stays in the steady state. On the other hand, there are various methods for determining the grey-level value of the image data of the area frame FRM_21. For example, the grey-level value of the area frame FRM_21 can be the maximum grey-level value among the image data of the area frame FRM_21. When the grey-level value of the area frame FRM_21 is within 0-255 (e.g., 8 bits are used for displaying the area frame FRM_21 in the display device 20), the PWM unit 104 can determine the width w21 of the on-period ON_21 as
if the grey-level value of the area frame FRM_21 is 20. Similarly, the PWM unit 104 can determine the widths of the on-periods of the other PWM signals according to the above description.
Please note that, the PWM unit 104 can determine the widths of the on-periods of the PWM signals such that the backlight driving unit 106 can configure the enabling times of the backlights of the display areas DA_11-DA_44 according to the widths of the on-periods. In the condition that the period of the PWM signal is fixed (which is proportional to the 1/Tf), the width of the on-period is corresponding to the width of the off-period. That is, the PWM unit 104 can determine the width of the off-period of the PWM signal for the backlight driving unit 106 to configure the enabling time of the backlight of the display area. Similarly, the width of the on-period is also corresponding to a duty-cycle of the PWM signal. The PWM unit 104 can determine the duty-cycle of the PWM signal for the backlight driving unit 106 to configure the enabling time of the backlight of the display area.
According to the above, the operation of the backlight control module 10 shown in
Step 400: Start.
Step 402: Configure a frequency of at least one PWM signal according to a frequency of a frame, when at least one area frame of at least one display area is used for displaying the frame.
Step 404: Configure at least one starting time instant of a period of the at least one PWM signal according to at least one starting time instant of the at least one area frame, respectively.
Step 406: Generate the at least one PWM signal and configure at least one width of at least one on-period of the period of the at least one PWM signal according to at least one image data of the at least one area frame, respectively, wherein the at least one on-period is located at an end of the period of the at least one PWM signal.
Step 408: End.
To sum up, the above embodiments provide a backlight control module and a backlight control method capable of not only adjusting the enabling times of the area frame of each display area according to the width of the on-period of the PWM signal to reduce the power consumption, decrease the light leakage and increase the dynamic contrast, but also decreasing the additional power consumption and eliminating the motion blur caused due to the transitions of the liquid-crystal.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Number | Date | Country | Kind |
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102115249 | Apr 2013 | TW | national |