Patent Application
20100066659
1. Field of the Invention
The present invention relates in general to a method and system of dynamic backlight modulation about images and in particular to a method and system of dynamic backlight modulation about images displayed on a liquid crystal display.
2. Description of the Prior Art
Hardware of a flat display, for example, backlight module, display or driving circuit, has been mature for many years not to play an important role on the improvement of display qualities that people still pursue. One of the qualities for display is relevant to the brightness (cd/m2) of the flat display. There are two methods to improve the brightness for display: increase the luminous flux of light of a LCD display and the brightness of background light. However, too bright display may fatigue a viewer's eyes. Reducing the contrast of pure white and pure black may degrade the performance of level and gray scale. Generally, contrast is the ratio of brightness respectively in the whole white and whole black display. For a traditional liquid crystal display, a cold cathode fluorescent lamp (CCFL) is used to the illumination unit of a backlight source. CCFL provides all of displayed frames with uniform brightness. Thus, one improvement way on the contrast to increase the contrast between a signal and a uniform gray scale is implemented by static enhancement technology. Another improvement way is to adjust the light flux by arranging the orientations of liquid crystals to generate darker hues. However, the alignment time of liquid crystals may cause the issue of light leakage in the neighborhood. Light leakage may further cause the display of a dark frame in a bright or blur way. Thus, it is still necessary to resolve the issue of the light leakage.
Currently, LED is used to the illumination unit of a backlight source for LCD. LED is advantageous to vivid display effect by the step control technology and the power reduction up to 80%. Compared with CCFL, LED has a higher performance on power utilization because light or dark brightness is efficiently controlled to meet with the brightness requirement of the images when LED is used as a light source of LCD. A two-dimensional backlight brightness control for the display of vivid visual effects, strong contrast, wide color range and good color saturation may be implemented by a set of addressable LED array.
There were various brightness control technologies in the backlight control of CCFL in the past years. For example, a zero-dimensional dimming technology satisfies the brightness requirement of images by making the whole backlight dark. One-dimensional modulation performs the modulation of single axis, for example, the brightness of one set of CCFL is modulated. The brightness control of the LED backlight has been developing to become workable because of the cost reduction of LED and the improvement of performance. Moreover, it is possible for LED to develop two-dimensional modulation (horizontal lines and vertical lines) because LEDs are arranged in an array easily and the array is easily controlled respectively. It was impossible for CCFL to be implemented in the past. For the two-dimensional modulation, most of light is emitted on the back of light area on a frame, and little light is emitted on the back of dark area on the frame. The control of two-dimensional LED backlight has more advantageous when the display is equipped with a RGB color LED, instead of a white LED. The RGB color LEDs may provide a wider color range for the brightness of a conventional backlight LCD panel. Thus, RGB backlight LED may provide brighter and higher saturation color display. For example, the color space of RGB may be mapped the color space of LED backlight with an adaptive saturation control. For such a mapping method, the saturation of a color may be as bright as one displayed by LED, without the changes of the white, skin and mild color of a frame or an image. The RGB LED in a two-dimensional array may be respectively controlled on the basis of monochromatic color so as to reduce the power consumption, improve the color range and contrast. For example, a color filter, which may absorb light to cause about 70% light loss, weights 19% in a total cost. The yield of a panel may be improved and the manufacturing cycle is reduced once the color filter is removed from a LCD panel. The removal of the color filter may improve 70% of the amount of emitting light to further reduce 70% of the amount of the LEDs, though LEDs as the backlight of LCD may raise 25% of the cost higher than CCFL as the backlight of LCD in field sequence process. The 70% reduction of LEDs means 70% reduction of the heat generated by the LEDs, as well as the power consumption. Furthermore, it is not necessary for the field sequence process to divide a pixel into three sub-pixels. Thus, the amount reduction of TFT may be up to ⅓ of the original amount of TFT which is equal to enlarge 3 times of the pixel area. That is, the triple resolution may be implemented based on a uniform screen dimension or a uniform pixel area.
Accordingly, it is a trend to improve the display quality by improving the distribution among signals and adjusting light source with the control of the two-dimensional LED backlight.
The present invention is directed to dynamically modulating and enhancing the contrast among signals for an input signal. Meanwhile, the drawbacks of the brightness with low contrast and too light black frame are improved by dynamically controlling the backlight of display.
The present invention is also directed to adjust brightness levels by dynamically modulating and enhancing the contrast among signals for an input signal. The input signal is modulated with the redistribution and the adjustment of backlight range based on the brightness levels to enhance the whole display quality of LCD display.
The present invention is directed to redistribute the distribution of signal intensity (gray scale average of signal) to generate a new transfer function. The primary input signal is converted by the transfer function to a transferred signal output for better display performance.
Accordingly, one embodiment of the present invention provides a system of dynamic two-dimensional backlight modulation. A gray-scale dividing unit is configured for receiving a gray-scale signal and dividing the gray-scale signal into a plurality of gray-scale zone signals. A gray-scale signal analyzing-and-separating unit electrically coupled to the gray-scale dividing unit is configured for receiving and analyzing the gray-scale zone signals for generating a gray-scale distribution average and a gray-scale distribution contrast average of the gray-scale signal. A gray-scale backlight modulation unit electrically coupled to the gray-scale signal analyzing-and-separating unit is configured for receiving the gray-scale distribution average and generating a gray-scale backlight control signal output according to the gray-scale distribution average. A gray-scale signal contrast enhancement unit electrically coupled to the gray-scale signal analyzing-and-separating unit is configured for receiving the gray-scale distribution contrast average and the gray-scale backlight control signal output to generate a variation of the gray-scale distribution contrast average. A unit of synthesizing-and-dividing gray-and-color light into RGB monochromatic light signal electrically coupled to the gray-scale signal contrast enhancement unit to compensate a RGB color signal is configured for varying the variation of the gray distribution contrast and converting the RGB color signal into the monochromatic light signal. A monochromatic dividing unit is configured for receiving a red, green or blue monochromatic signal and dividing the red, green or blue monochromatic signal into a plurality of monochromatic zone signals. A monochromatic signal analyzing-and-separating unit electrically coupled to the monochromatic dividing unit is configured for receiving and analyzing the monochromatic zone signals for generating a monochromatic distribution average and a monochromatic distribution contrast average of the monochromatic signal. A monochromatic backlight modulation unit electrically coupled to the monochromatic signal analyzing-and-separating unit is configured for receiving the monochromatic distribution average and the gray-scale backlight control signal output to generate a red, green or blue backlight control signal output. A monochromatic signal contrast enhancement unit electrically coupled to the monochromatic signal analyzing-and-separating unit is configured for receiving the monochromatic distribution contrast average and the red, green or blue backlight control signal output to generate a RGB color-mixed signal.
A method of dynamic two-dimensional backlight modulation includes the following steps: dividing a gray-scale signal into a plurality of gray-scale zone signals; analyzing the gray-scale zone signals for generating a gray-scale distribution average and a gray-scale distribution contrast average of the gray-scale signal; generating a gray-scale backlight control signal output according to the gray-scale distribution average; generating a variation of the gray-scale distribution contrast average according to the gray-scale distribution contrast average and the gray-scale backlight control signal output; compensating a RGB color signal for varying the variation of the gray distribution contrast and converting the RGB color signal into the monochromatic light signal; dividing a red, green or blue monochromatic signal into a plurality of monochromatic zone signals; analyzing the monochromatic zone signals for generating a monochromatic distribution average and a monochromatic distribution contrast average of the monochromatic signal; generating a red, green or blue backlight control signal output according to the monochromatic distribution average and the gray-scale backlight control signal output; and generating a RGB color-mixed signal according to the monochromatic distribution contrast average and the red, green or blue backlight control signal output.
Other advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of the present invention.
These features, aspects and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings, which illustrate examples of the invention. However, it is to be understood that each of the features can be used in the invention in general, not merely in the context of the particular drawings, and the invention includes any combination of these features, where:
The present invention relates in general to a method and system of dynamic backlight modulation about images. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiments and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein.
Next, the signal analyzing-and-separating unit 104 electrically coupled to the dividing unit 102 outputs the distribution contrast average 107 to a signal contrast enhancement unit 106. The signal contrast enhancement unit 106 judges whether a maximum light level and a minimum light level corresponding to the intensity of the signal are within a default range, and adjusts backlight compensation with the gray-scale backlight control signal output 109. Accordingly, the ratio of signals may be extended to enhance the fine portion of an image on a screen. The enhanced distribution contrast average 107 is then outputted to a unit of synthesizing-and-dividing gray-and-color light into RGB monochromatic light 108. The unit of synthesizing-and-dividing gray-and-color light into RGB monochromatic light 108 compensates a primary RGB color signal input 111 for the variation of the distribution contrast 107 and converting the RGB color-mixed signal 113 by synthesizing the primary RGB color signal input 111 and the variation of the distribution contrast 107. The orientations of liquid crystals are controlled by the RGB color-mixed signal 113 to adjust a flux of RGB primary color light. The modulation technology aforementioned may be applied to white light LED backlight for a display.
Next, for the modulation of RGB color light LED backlight, a dividing unit 102 is configured for receiving the converted RGB color-mixed signal 113 from the unit of synthesizing-and-dividing gray-and-color light into RGB monochromatic light 108 and dividing the converted RGB color-mixed signal 113 receptively into a plurality of monochromatic zone signals 115. Another signal analyzing-and-separating unit 104 electrically coupled to the dividing unit 102 is configured for receiving and analyzing the zone signals 115 of each monochromatic light signal to generate a distribution average 117 and a distribution contrast average 119 of the RGB color signal input 111. The RGB monochromatic backlight modulation unit 112 electrically coupled to the signal analyzing-and-separating unit 104 is configured for receiving the distribution average 117 to generate a red, green or blue backlight control signal output 121 according to the distribution average 117. The red, green or blue backlight control signal output 121 is used to control a RGB monochromatic backlight module (not shown in the figure) for the lightness of a light source within a predetermined range. Furthermore, a signal contrast enhancement unit 106 electrically coupled to the signal analyzing-and-separating unit 104 is configured for receiving the red, green or blue color light distribution contrast average 119. The signal contrast enhancement unit 106 judges whether a maximum light level and a minimum light level corresponding to the intensity of the signal are within a default range, and adjusts backlight compensation with the red, green or blue backlight control signal output 121 to output a red, green or blue monochromatic light signal. Accordingly, the ratio of signals may be extended to enhance the fine portion of an image on a screen. The enhanced red, green or blue color light distribution contrast average 119 is outputted to the unit of synthesizing-and-dividing gray-and-color light into RGB monochromatic light 108 and then converted into the RGB color-mixed signal 113. The orientations of liquid crystals are controlled by the RGB color-mixed signal 113 to adjust a flux of RGB primary color light. The two-dimensional modulation technology aforementioned may be applied to the red, green or blue color LED backlight for a display.
A method of dynamic contrast enhancement may be acquired according to the system aforementioned. Referring to
Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that other modifications and variation can be made without departing the spirit and scope of the invention as hereafter claimed.
