Patent Application
20180090077
The present disclosure relates to display technical field, and more particularly to a liquid crystal display apparatus and a backlight control method thereof.
Nowadays, in the popular mobile phone and flat panel display apparatus, backlight part is the part having the largest power consumption, and the tendency of lightening and thinning the mobile phone and flat panel display apparatus extremely limits variability in size and capacity of the battery. For solving the problems of limitation to capacity of the battery as well as reduction of power consumption, Content Adaptive Brightness Control (CABC) technology is widely used. CABC technology is a backlight power-saving technology that is mainly used in Liquid crystal Display (LCD) screen.
In particular, CABC technology can adjust, according to an image displayed on the screen, a relation between gray level and screen backlight brightness of the image, and substantially maintain the display effect of the image while effectively reducing the screen backlight brightness. For example, the image is brightened by enhancing the gray level by 30%, and the image is darkened by reducing the backlight brightness of the LCD screen by 30%, thus the brightness presented by the image is substantially maintained the same before and after processing, and the power consumption of backlight is reduced by 30%. Backlight brightness can be controlled according to magnitude of driving voltage. An existing liquid crystal display apparatus using CABC technology is shown in
In the liquid crystal display apparatus having the structure mentioned above, the dimming mode of the backlight is a single mode of performing pulse width modulation to the backlight driving signal SPWM. PWM dimming has high conversion efficiency when the required backlight brightness is large; but the duty ratio of PWM dimming is very low when the required backlight brightness is small, which greatly reduces the efficiency of backlight driving, and goes against the effective use of the entire system energy of the liquid crystal display apparatus.
To this end, the present invention provides a liquid crystal display apparatus and a backlight control method thereof. The liquid crystal display apparatus, using the CABC technology, improves overall efficiency of backlight driving by improving the backlight control structure and method.
To achieve the above purpose, the present invention uses the following technical solution:
A liquid crystal display apparatus, comprising an image data acquisition part, a liquid crystal panel, a panel driving unit, a backlight module and a backlight driving unit, wherein, the image data acquisition part is used to acquire image data; the panel driving unit drives the liquid crystal panel according to the image data and generates a backlight driving signal corresponding to the image data; the backlight driving unit comprises a Pulse-Width Modulation (PWM) module and a Pulse-Frequency Modulation (PFM) module, and one of the PWM module and the PFM module modulates the backlight driving signal during one display period to form a driving power supply to be supplied to the backlight module; and the liquid crystal display apparatus further comprises a backlight modulation selection unit which is used to detect and calculate an average pixel brightness value A of the image data, and a reference pixel brightness value A0 is also set in the backlight modulation selection unit; when A≧A0, the backlight modulation selection unit selects to enable the PWM module; and when A<A0, the backlight modulation selection unit selects to enable the PFM module.
Wherein the backlight modulation selection unit comprises an average pixel brightness detection module and a pixel brightness comparison module, wherein the average pixel brightness detection module is used to detect and calculate the average pixel brightness value A of the image data, the pixel brightness comparison module is used to store the reference pixel brightness value A0 and compare the average pixel brightness value A with the reference pixel brightness value A0.
Wherein the average pixel brightness detection module acquires the image data, and obtains the average pixel brightness value A through analysis and calculation on a gray histogram.
Wherein the reference pixel brightness value A0 is 5%-25% of the maximum value of pixel brightness of the image data acquired by the image data acquisition part.
Wherein the panel driving unit receives image data from the image data acquisition part and increases gray level brightness of the image data according to a numerical ratio, so as to drive the liquid crystal panel; and the panel driving unit generates the backlight driving signal according to the condition that enables the backlight module to reduce the backlight brightness in accordance with the numerical ratio.
Wherein the numerical ratio is preset and is written in the panel driving unit by a register.
A backlight control method of the above mentioned liquid crystal display apparatus, the backlight control method comprises: receiving image data from the image data acquisition part by the panel driving unit, to generate a backlight driving signal corresponding to the image data; detecting and calculating the average pixel brightness value A of the image data by the backlight modulation selection unit, and comparing the average pixel brightness value A with the reference pixel brightness value A0, when A≧A0, the backlight modulation selection unit selects to enable the PWM module, and the PWM module modulates the backlight driving signal to form a driving power supply to be supplied to the backlight module; and when A<A0, the backlight modulation selection unit selects to enable the PFM module, and the PFM module modulates the backlight driving signal to form a driving power supply to be supplied to the backlight module.
Compared with the prior art, according to the liquid crystal display apparatus and the backlight control method provided in the embodiments of the present invention, the liquid crystal display apparatus using CABC technology, a backlight driving unit therein includes a Pulse-Width Modulation (PWM) module and a Pulse-Frequency Modulation (PFM) module, to determine the required backlight brightness level by detecting and calculating the average pixel brightness value of the image data; when large backlight brightness is required, PWM dimming may have a high conversion efficiency, and the PWM module modulates the backlight driving signal to form a driving power supply to supply to the backlight module; and when small backlight brightness is required, PFM dimming may have higher conversion efficiency, thus the PFM module modulates the backlight driving signal to form a driving power supply to supply to the backlight module. Base on this, the overall backlight driving efficiency is improved by improving the backlight control structure and method.
Hereinafter, the technical solutions in embodiments of the present invention will be described in details with reference to the attached drawings and details embodiments. Obviously, the described embodiments are only a part of embodiments in the present invention, not all embodiments. Based on the embodiments of the present application, all the other embodiments acquired by those ordinarily skilled in the art without exerting any creative efforts fall within a protection scope of the present application.
Here, it also should be explained that the figures merely show structures and/or processing steps which are closely associated with the scheme of the present invention, while other details which do not do much about the present invention are omitted in order to avoid unclearness of the present invention due to unnecessary details.
The present embodiment provides a liquid crystal display apparatus, which uses a new backlight control method. The method improves overall backlight driving efficiency by improving the backlight control structure and the backlight control method based on CABC technology. In particular, as shown in
The image data acquisition part 10 serves to acquire each frame of the image data SRGB that needs to be displayed by the liquid crystal display apparatus, and to input each frame of the image data SRGB to the panel driving unit 30. The panel driving unit 30 drives the liquid crystal panel 20 according to each frame of the image data SRGB and further generates backlight driving signals SPWM corresponding to each frame of the image data SRGB. The backlight driving unit 50 modulates the backlight driving signal SPWM to form driving power supply VL1 and VL2 to supply to the backlight module 40 such that the backlight module 40 generates a display light source having corresponding brightness to supply to the liquid crystal panel 20, and the liquid crystal panel 20 displays an image. The backlight modulation selection unit 60 serves to detect and calculate an average pixel brightness (namely, Average Picture gray Level (APL)) value of each frame of the image data SRGB from the image data acquisition part 10, and judges the brightness level of the backlight light source that needs to be provided by the backlight module 40 by comparing the detected and calculated APL value with a reference pixel brightness value preset in the backlight modulation selection unit 60 according to the detected and calculated APL value, to control the mode of the modulation (pulse width modulation mode or pulse frequency modulation mode) to the backlight driving signal SPWM performed by the backlight driving unit 50, thereby improving backlight driving efficiency.
Specifically, as shown in
In particular, as shown in
Furthermore, the backlight control method of the above mentioned liquid crystal display apparatus mainly includes:
(1) using CABC technology: In an aspect, the panel driving unit 30 enhances the gray level brightness of the image data SRGB according a numeral ratio, to form corresponding driving signal to be input to the liquid crystal panel 20; In another aspect, the panel driving unit 30 generates the backlight driving signal SPWM based on the condition that enables the backlight module 40 to reduce the backlight brightness in accordance with the numeral ratio. Where the numeral ratio is a percentage value, it is preset (it can be set according to specific image to be displayed and client's demanded power-saving effect) and is written in the panel driving unit 30 by a register. CABC technology is a mature existing technology, thus the scope of the value is no longer specifically defined herein. In general, the value is selected as 30%, the image is brightened by enhancing the gray level of the image data SRGB by 30%, and the image is darkened by reducing the backlight brightness by 30%, thus the brightness presented by the image is maintained almost the same before and after processing, and the power consumption of its backlight is reduced by 30%.
(2) judging the brightness level of the backlight light source that needs to be provided, and selecting the corresponding dimming modes: the backlight modulation selection unit 60 detects each frame of the image data SRGB from the image data acquisition part 10, to calculate the average pixel brightness value A through analysis of a gray histogram, and compares the average pixel brightness value A with the reference pixel brightness value A0. When A≧A0, the backlight modulation selection unit 60 selects to turn on the PWM module 51 to perform pulse width modulation on the backlight driving signal SPWM, so as to form the driving power supply VL1 to supply to the backlight module 40; and when A<A0, the backlight modulation selection unit 60 selects to turn on/enable the PFM module 52 to perform the pulse frequency modulation on the backlight driving signal SPWM, so as to form the driving power supply VL2 to supply to the backlight module 40.
In conclusion, according to the liquid crystal display apparatus and the backlight control method thereof provided by embodiments of the present invention, the backlight power consumption is reduced by the liquid crystal display apparatus using CABC technology. The backlight driving unit therein includes a Pulse-Width Modulation (PWM) module and a Pulse-Frequency Modulation (PFM) module, to determine the required backlight brightness level by detecting and calculating the average pixel brightness value of the image data; that is: when large backlight brightness is required, a PWM dimming mode having higher efficiency on this occasion is used; and when small backlight brightness is required, a PFM dimming mode having higher efficiency on this occasion is used, thereby improving overall backlight driving efficiency.
It should be explained that the relationship terms, such as first and second, etc., in the present text are only used for distinguishing one entity or operation from another entity or operation without requiring or implying any actual relation or sequence existing between these entities or operations. Moreover, the term “include”, “contain” or any other variant means covering instead of exclusively including, so that the process, method, object or device including a series of factors not only includes those factors but also includes other factors that are not explicitly listed or further include inherent factors for this process, method, object or device. Where no more limitations are provided, the factors defined by the sentence “include one . . . ” do not exclude additional identical factors existing in the process, method, object or device which includes the factors.
Obviously, the protection scope of the present invention is not limited to the above detailed modes of carrying out the invention, and those skilled in the art may make various changes and modifications to the invention without departing from the scope and spirit of the invention. As such, if these changes and modifications of the present invention belong to the scope of the claims of the present invention and equivalent technologies thereof, the present invention also intends to include these changes and modifications here.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201610146214.9 | Mar 2016 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2016/078255 | 4/1/2016 | WO | 00 |
